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The APS in an Age of Litigation

Harry Lustig

Read as an invited paper at the March 2000 meeting of the American Physical Society in a session "Physics and the Law" arranged by the Forum on Physics and Society. Most of the material is adapted from the author’s article in the American Journal of Physics

For the first eighty-seven years of its existence, the APS had never been involved in a lawsuit. Since 1987, the Society defended itself in the courts in four cases. All of the litigation was connected with publishing. Two plaintiffs sued the Society for not publishing their work, one sought to punish APS for publishing an author’s work, and in one case, a third party attempted to compel the Society to reveal the identity of a referee of a manuscript that was not accepted for publication.

In spite of the fact that the Physical Review almost certainly provides more opportunities to appeal the recommendations of referees and the decisions of editors than any other journal, there have been aggrieved authors before and since. A few have turned nasty--for example, editors and the Society were accused of being part of a Jewish conspiracy to prevent the dissemination of a refutation of Einstein’s relativity. Some have implicitly or explicitly threatened lawsuits, but before 1987, none of these threats ever materialized.

In 1987, the APS was notified that it was the defendant in a federal suit seeking damages of $44,500,000. The plaintiff, who had very limited training in physics, alleged that the Society had deprived her of seven Nobel prizes by rejecting a manuscript that she had submitted to the Physical Review. She claimed that her invention, the "Qaddafi Field", encompassed and replaced all the fundamental laws of physics. (She is also reported to have said the APS had tried to poison her coffee and had killed Physical Review D editor Dennis Nordstrom for having promised to accept her manuscript. Her estranged husband reported that she was carrying a gun.) The courts were able to deal swiftly with the case, although the plaintiff, who represented herself, did try to pursue her complaint all the way to review by the Supreme Court. This bizarre and depressing case had perhaps one redeeming aspect: it showed that every citizen who feels aggrieved can access our judicial system.

The other instance in which the APS was accused of improperly refusing to publish an article presented quite a different issue. Physical Review A had accepted an article by a University of Maryland research associate, Thomas Kiess, for publication. When his colleagues found out about it through prepublication of the abstract, they complained that the work had been done collaboratively with them, and that publishing the article without recognition of them would be improper. The editors of the Physical Review decided to suspend publication unless and until the matter could be resolved. Kiess thereupon sued his collaborators and the APS, claiming that the refusal by the Physical Review to proceed with the publication of his manuscript after he had received notification of its acceptance, constituted a breach of contract . The APS responded that there was no contract, that the Physical Review’s letter of acceptance contained conditions that were never satisfied, and that even if the parties had created a contract, there was no breach because the journal had not refused to publish the manuscript. The court agreed and dismissed the case against the APS.

Again in 1987, the APS was served with a subpoena by attorneys for Arco Solar, the defendant in a patent infringement case brought by Solarex Corporation and RCA Corporation. Arco Solar sought the name of a referee for a manuscript that described results that could improve amorphous silicon p-n junctions. The manuscript was submitted to Physical Review Letters but was rejected for publication based on the strength of one of the two referees’ reports. The report requested that more experiments were required and that the article was better suited for the Physical Review. The other referee had recommended publication and had revealed his name and his action to the authors. As an element of its defense strategy, Arco Solar wanted to maintain that the submission constituted "prior art" which invalidated the patent at issue. The idea was to try to claim that the negative referee had disclosed the new process to colleagues and, perhaps, to other competitors. In order to pursue this theory, Arco Solar needed to know the identity of the referee.

While willing to turn over the referee’s opinion and all other documents connected with the case, the APS remained true to the common practice in scientific publishing and declined to reveal the name of the referee. APS’s attorney, Richard A. Meserve, argued that non-disclosure was essential to the preservation of the peer-review process. (Meserve is a physicist and was a lawyer until late 1999 when he became head of the Nuclear Regulatory Commission. He has successfully represented the Society in all the cases described here.) The US Magistrate who heard the case found unequivocally in favor of APS, observing that "...the Society had demonstrated a strong interest in preserving the confidentiality of its reviewer’s identity", and the District Court and the Court of Appeals affirmed the ruling. The decision, while not establishing an absolute right to keep the names of referees confidential, nevertheless provided a presumptive precedent for it. David Lazarus, APS’s quondam editor-in-chief, had the satisfaction of being able to report on theoutcome in Physics Today.

The most vexing litigation against APS, directed against AIP and an individual APS member, by the Gordon & Breach publishing group and its several companies, has, at this writing, for more than a decade. It has its origins in two articles by H. H. (Heinz) Barschall of the University of Wisconsin, one written with a collaborator, which reported the cost per printed character, the impact, and the cost-effectiveness of more than 200 physics journals from nearly sixty publishers . The cost per printed character (perhaps better "price per printed character") is the amount paid by an American library for an annual subscription to a journal divided by the total number of characters published in that journal during the year. (In order to neutralize the effect of variations in typography and page size, Barschall used characters rather than pages, in the denominator.) The impact is the average number of times that articles from a journal were cited during the two years following their publication, as determined by the Institute for Scientific Information. It was Barschall’s innovation also to obtain and report the quotient of the price per character divided by the impact, resulting in the cost-effectiveness.

Barschall’s study showed that the Gordon & Breach journals were by far the most expensive and least cost- effective in the survey - not only when compared to those of not-for-profit societies such as APS and AIP, but also to those of other commercial publishers. This result was not explicity pointed out in the articles, however, readers could calculate that there was a factor of eighty difference between the journal with the highest price per character on the list, Gordon & Breach’s Physics and Chemistry of Liquids, and that with the lowest, the American Astronomical Society’s Astrophysical Journal. With the impact figured in, the cost-effectiveness difference between these two journals became a factor of 409.

The officers of the two societies and Barschall were surprised to receive complaints from lawyers for Gordon & Breach against the articles and a demand, under threat of litigation, for the publication of a prescribed retraction and an apology. Barschall and the societies checked the allegations of error and concluded that they were either without foundation or insignificant. Nevertheless, Physics Today offered Gordon & Breach space for a statement setting out its objections to the Barschall articles, subject only to allowing the author to respond to allegations of error. This offer was summarily rejected. This offer for resolving the complaint was maintained by APS and AIP during the many years of the ensuing litigation.

As to the threats of a lawsuit, the officers of the societies found it hard to believe that the accuracy of Barschall’s study and the action of the societies in publishing it would even be considered by the courts on their merits. Wasn’t there a constitutionally guaranteed right of free speech and publication? In 1989, when suits were launched in Germany, Switzerland, and France against Barschall, APS, and AIP, the defendants had to contend with the fact that free speech protection was not as strong in those countries as in the United States. "Unfair competition" laws significantly restricted the right, even truthfully and accurately, to compare the prices and quality of products. The suits demanded retractions and the publication of prescribed apologies in the Bulletin and in Physics Today, injunctions against the publication of any further studies by Barschall or by anyone applying similar methodologies, and damages.

Even in the face of the strict laws, but at great effort and expense, Barschall and the Societies won their cases in Germany (as early as 1991 after unsuccessful appeals by Gordon & Breach all the way to the federal supreme court [Bundesgericht]) and in Switzerland. In France, in the face of a law that Gordon & Breach would interpret to forbid any comparison of the prices of products that are not completely identical, the trial court found against the defendants. After several see-saw actions, the Court D’Appel, on 21 June 2000, dismissed the G&B complaints against the societies and Barschall’s heirs (Barschall had died on February 4, 1997) one by one, finding that the articles were neither denigrating, misleading, nor in other way in violation of French law. At this writing is not clear whether G&B will be allowed to file yet another appeal before the Court de Cassation.

APS and AIP had another unwelcome surprise when, on September 23, 1993, Gordon & Breach filed suit in the United States under a statute called the Lanham Act, which regulates advertising, stating that "commercial speech" must not be false or misleading. The pursuit of the litigation in the US exceeded, in effort and cost, even the burdensome activities in Europe. Dozens of briefs and counter-briefs were filed and motions were made; hundreds of documents were produced, and more than a score of witnesses were examined by deposition or at trial.
In August of 1994 the Federal District Court for the Southern District of New York issued its first substantive decision. He dismissed the Lanham Act claims against Physics Today and the Bulletin because, as scholarly publications, they enjoyed the protection of the First Amendment to the US Constitution. The matter did not rest there, because Gordon & Breach asserted that "secondary uses" (which included the distribution of a draft to some librarians at a convention and the favorable mention of the Barschall findings in the 1988 annual presidential letter to the membership by APS President Val Fitch, which included the phrase "tell your librarian about it" ) had been made of the articles, and the judge ruled that these uses of the survey should be subject to examination under the Lanham Act..

The ruling opened the way to "discovery" of documents from APS’s, AIP’s and Barschall’s files, which were used by the plaintiffs to try to make a case that the research and publication of Barschall’s findings resulted from a conspiracy between the authors and the societies to hide the alleged commercial intent of the undertaking. The allegation of a conspiracy was based largely on the fact that before the initiation of the survey there had been some consultation between Barschall and APS and AIP officials about whether a survey would be useful, and while it was in progress, some correspondence about Barschall’s work. During one of these exchanges the APS treasurer made the suggestion that Barschall might explicitly mention the favorable results for the societies’ journals. The suggestion was rejected.

The reason put forward by Gordon & Breach for the societies’ allegedly enlisting Barschall in a marketing effort was their need to maintain library subscriptions in the face of sharply increased prices. While it is true that prices had to be raised, in the face of declining numbers of subscriptions and of income from page charges, most of the increase was necessitated by the steep increases in the numbers of articles submitted and published. The societies clearly welcomed the news that, in spite of the increases, their journals were still extremely cost-effective. Some in AIP and APS did see an advantage in publicizing the results among librarians while others saw their value in justifying the painful price increases that were necessary to keep the journals solvent.

After a seven day trial in June of 1997, Barschall’s methodology was deemed sound and the results free from errors. The court also found that the Gordon & Breach complaint that Barschall did not examine or report on the costs to them of producing their journals was irrelevant. More significantly, the court gave credence to the societies’ discovery, during the long years of litigation, that "the evidence persuasively demonstrated that the present suit is but one battle in a ‘global campaign by G&B to suppress all adverse comments upon its Journals’ ". APS and AIP were able to document ten instances of (mostly successful) attempts at intimidation, including of librarians, professors and research scientists in the US and abroad. In January of 1999 the U.S. Court of Appeals for the Second Circuit rejected Gordon & Breach’s appeal of this decision.

Except for one possible final appeal by G&B in France, this appears to be the end of the case. APS and AIP can celebrate not only their victory (tempered only by the fact that Barschall, did not live to see it) but also their steadfastness and willingness, in the face of a large drain of money. The credit for this persistence belongs not only, or even primarily to the determined operating officers (in the case of AIP, first Kenneth Ford and then Marc Brodsky), but to the Council and Executive Board of APS and the Governing Board of AIP. On the many occasions on which the case came before these bodies for discussion and decision, in the face of some sentiment to settle it, even on restrictive and dangerous terms, the representatives of the membership stood firm. Among the APS presidents during the period, Burton Richter and Kumar Patel should be singled out for their steadfast leadership; in the AIP, Hans Frauenfelder led the Governing Board in refusing to abandon the case, except on honorable terms. Although, the case had no broad economic implications for AIP and APS, the societies pursued it as a battle in defense of truth, free expression and the competence and integrity of a valued member.

Harry Lustig
Professor of Physics and Provost Emeritus
City College of the City University of New York
Treasurer Emeritus of the American Physical Society
Adjunct Professor of Physics at the University of New Mexico.

References/Footnotes

1. H. Lustig, "To Advance and Diffuse the Knowledge of Physics--an account of the one-hundred year history of the
2. American Physical Society", Am. J. Phys. 68, 595 (2000).
3. Kiess v. Rubin, Civ. No 95-CV-01267 (Md. Cir. Ct. 1995)
4. Solarex Corp. v Arco Solar, Inc., 121 F.R.D. 163, 179 (E.D.N.Y. 1988); Arcos Solar, Inc. v. American Physical
5. Society, 870F.2d 642 (Fed. Cir. 1989)
6. David Lazarus, "In Defense of Confidentiality", Phys. Today 42, 57 (1989).
7. Henry H. Barschall, "The cost-effectiveness of physics journals", Phys. Today 41, 56 (1988).
8. H.H. Barschall and J.R. Arrington, "Cost of physics journals: a survey", Bull. Am. Phys. Soc. 33, 1437-1447 (1988).
9. Gordon and Breach Science Publishers S.A. v American Institute of Physics, 859 F. Supp. 1571 (S.D.N.Y. 1994).
10. OPA (Overseas Publishing Ass'n) Amsterdam B.V. v. American Inst. of Physics, 973 F. Supp. 414 (S.D.N.Y. 1997)
11. Irwin Goodwin, "Federal Court Rules for APS and AIP in Dispute with Gordon & Breach over Survey of Journals", Phys. Today 49, 10 (1997).
12. Extensive documentation about this case is available on the Web at http://barschall.stanford.edu and at http://www.library.yale.edu/barschall

Experiments In International Benchmarking of U.S. Research Fields

Marye Anne Fox and Robert M. White
As a nation, we support a large research enterprise, whose funding must be consistently and fairly allocated. At present, there is no reliable tool to allow for the evaluation of the quality of federally funded research programs and provide a basis for the subsequent allocation of funds to those programs. The National Academies Committee on Science, Engineering, and Public Policy (COSEPUP) has been testing the validity of international benchmarking, comparing the quality and impact of research in one country or region with world standards of excellence, as a possible tool for funding allocation. COSEPUP has run a series of experiments to test the use of benchmarking as a tool to understand the relative world standing of US research in a field and to understand the factors that are critical to US leadership in that field. This article describes the background behind benchmarking and the methodologies and results of COSEPUP’s experiments in internationally benchmarking three fields: mathematics, materials science and engineering, and immunology.

Background
In 1993, COSEPUP issued its report Science, Technology, and the Federal Government: National Goals for a New Era, which recommended that the federal government should continue vigorous funding of basic research and to seek to support basic research across the entire spectrum of scientific and technological investigation. Specifically, the report made two recommendations: First, that

"The United States should be among the world leaders in all major areas of science,"

and second, that

"The United States should maintain clear leadership in some major areas of science."

By following these recommendations, the U.S. would position itself among world leaders in all major fields of research and would be ready to apply and capitalize on research advances wherever they may occur.

Two years later, in 1995, a committee (on which I was a member) chaired by Frank Press, the former president of the National Academy of Sciences, stated that "to continue as a world leader, the United States should strive for clear leadership in the most promising areas of science and technology and those deemed most important to our national goals. In other major fields, the United States should perform on a par with other nations so that it is ‘poised to pounce’ if future discoveries increase the importance of one of these fields."

The committee also considered how the federal government could gauge the overall health of the research enterprise and determine the adequacy of national funding and whether it is supportive of national research objectives. The committee wrote that it is possible to monitor US performance with field-by-field peer assessments, which may be accompanied by:

"...the establishment of independent panels consisting of researchers who work in a field, individuals who work in closely related fields, and research ‘users’ who follow the field closely [can provide that kind of evaluation]. Some of these individuals should be outstanding foreign scientists in the field being examined."

The technique of comparative international assessments, or what we at COSEPUP came to call "international benchmarking," had been discussed at that time, but had not been practiced. From this, COSEPUP made the decision to undertake a set of experiments to test the utility of international benchmarks in evaluating entire research fields.

The committee acknowledged that quantitative indicators which are often used to assess research programs — for example, dollars spent, number of papers cited, and number of researchers supported all provide valuable information, but by themselves are not sufficient indicators of leadership. This quantitative information is often difficult to obtain or compare across national borders, illuminates only a portion of the research process.

COSEPUP decided that benchmarking should rely more prominently on the judgement of experts. The premise for this decision was that only leaders of a particular research field are in a position to judge leadership. COSEPUP charged each panel to provide answers to three primary questions:

1. What is the position of US research in the field, relative to that in other regions or countries?
2. On the basis of current trends, what will be our relative position in the near and longer-term future?
3. What are the key factors influencing relative US performance in the field?
4. The committee deliberately chose three fields that have a range of scope and subject matter. Of the three, mathematics is the closest to being a traditional discipline, but is broad in the sense that it has a language and is a tool used by other research fields. Immunology is not a disciplinary field in the traditional sense–it embraces many disciplines including biochemistry, genetics, and microbiology. Like immunology, materials science and engineering have even a broader span of disciplines.

Benchmarking Methodology
Determining how one country stands relative to another in science involves a great deal of subjective judgement. The first critical step in an international benchmarking process is the selection of panel members. Once selected, each panel divided their field into subfields. Then each panel used a variety of methods to assess their subfields, including:

• "Virtual congress"
• Citation analysis
• Journal publication analysis
• Quantitative data analysis (e.g., number of graduate students, funding)
• Prize analysis
• Invited speakers at international congresses

The first method used was the "virtual congress," where each panel asked leading experts in the field to identify the "best of the best" researchers for particular subfields, anywhere in the world. For example, the panel members of the materials science and engineering panel asked colleagues, for nine different subfields, such as ceramics and polymers, to identify five or six current hot topics and eight to ten of the best researchers in the world. The information was used to construct tables that characterized the relative position of the United States in each of the subfields.

While the "virtual congress" may determine how the U.S. currently stands relative to other countries, additional factors must be considered to predict its future ranking. The materials science and engineering panel developed what it called "determinants of leadership." These are factors that indicate the level of research likely to occur in the future. They include:

• National Imperatives
• National Innovation Systems
• Major Facilities
• Human Resources
• Funding

National imperatives refer to national objectives, whose byproducts are likely to produce scientific leadership. The Cold War, for example, drove the development of materials for stealth aircraft.

Another method used by the panels was citation analysis, which is traditionally used to evaluate the international standing of a country’s research in a field. Each panel used an analysis by the United Kingdom Office of Science and Technology to evaluate US research quality. This analysis included both the numbers of citations and the "relative citation impact", which compares a country’s citation rate (the number of citations per year) for a particular field to the worldwide citation rate for that field. This latter measure takes into account the size of the US enterprise relative to that in other countries. (See the Web edition of this issue for tables containing some illustrative numerical results. [powerpoint format file])

The immunology panel used a method called "journal publication analysis." The panel identified four leading general journals and one of the top journals that focused specifically on immunology. Panel members analyzed the tables of contents of each of the journals. In the general journals, they identified immunology papers and the laboratory nationality of the principal investigator; and in all the journals, they identified subfields. That allowed a quantitative comparison between publications by US-based investigators and publications by investigators based elsewhere.

The panels found it difficult to obtain suitable, unbiased quantitative information which would allow comparisons of the major features of the scientific enterprise, (e.g. education, funding and government agencies) in different countries. Mathematics was among those exceptions and illuminates the use of human resources as a consistent source quantitative data. Taken from the American Mathematical Society, attachment III shows that the number and proportion of non-US PhD recipients in mathematics increased by 78% from 1985 to 1995. Furthermore, in every year since 1990, foreign students have received more than half the PhDs awarded in mathematics in the United States.

Each of the panels analyzed the key prizes given in its field. For example, in mathematics, the key international prizes are the Fields medal and the Wolf prize. The numbers of non-US and US recipients of these medals were analyzed on the basis of where they now conduct their research.
Another condition that can be quantified is representation among the plenary speakers at international conferences. Although conference organizers strive for geographic balance by inviting speakers from different countries, speakership is a useful indicator of quality by comparing the relative number of US invited speakers to the relative number of publications.

Benchmarking Results
Each panel concluded that the US was at least among the world leaders in its field. However, each panel identified subfields in which the United States lagged the world leaders. Each panel also identified key infrastructure concerns.

The mathematics panel found that although the United States was currently the world leader in mathematics, this leadership was dependent upon foreign talent that came to the United States particularly preceding and during World War II and following the collapse of the Soviet Union. The difficulty of attracting U.S. talent to mathematics today and the unpredictability of recruiting foreign talent led the panel to be concerned about the future leadership status of the United States in this field.

In materials science and engineering research, the U.S. was among the few world leaders in this field. Other countries are more aggressively pursuing research in this field, as it is essential to economic growth. A particular concern is that major facilities are newer in other countries than in the United States, such as neutron sources in Europe and Japan, which are younger than U.S. sources by 20-30 years.

A panel found that the U.S. was the world leader in immunology. Despite the fact that U.S. financial investment in this field overshadows that of other countries, the U.S. was not the leader in all subfields. Of particular concern was clinical immunology since restrictions of managed care systems in the U.S. versus other countries make it more difficult to attract the patients needed for clinical studies.

COSEPUP Analysis of Benchmarking Experiments
After the panels’ work was completed, COSEPUP evaluated panel results independently along with comments from participants in a workshop, which included White House, congressional staff, and agency staff and disciplinary societies. The reviewers who took part in the National Academies normal report review process were of particular importance, as they are chosen to represent diverse industrial and academic backgrounds.
Based on these deliberations, COSEPUP found international benchmarking to be rapid and inexpensive compared with procedures that rely entirely on the assembly of a huge volume of quantitative information. In the words of one panel chair, "We were able to get 80% of the value in 20% of the time, for a far lower cost."

COSEPUP also found good correlation between findings produced by different indicators. For example, the qualitative judgments of the virtual congress were similar to the results of quantitative indicators, such as publications cited or papers delivered at international congresses. Lending credence to the technique was a parallel benchmarking experiment in mathematics conducted by the National Science Foundation that produced similar results to COSEPUP's math study, despite differences in panel makeup and the mandates of each organization.

The Government Performance and Results Act of 1993 (GPRA) emphasized the need for a method to assess the fruits of scientific and technological research investments by the federal government. COSEPUP’s GPRA report in 1999 concluded that the most effective means of evaluating federal research is to provide expert review of the quality, relevance, and leadership of research programs. Some elements of benchmarking may indeed provide useful input to agency strategies to comply with GPRA.

In summary, COSEPUP concluded that this experiment should be regarded as an encouraging first step toward the design of an efficient and reasonably objective evaluation tool. Additional benchmarking exercises could lead to more effective assessment methods, better understanding of the factors that promote research excellence, and better decision-making by those who fund science and technological innovation

Marye Anne Fox
Chancellor, North Carolina State University
Office of the Chancellor Box 7001/A Holladay Hall Raleigh, NC 27695-7001
(919) 515-2191 Fax: (919) 831-3545

Robert M. White
Laboratory for Advanced Materials Dept. of Materials Science and Engineering
Jack McCullough Bldg., Rm. 349, MC 4045 476 Lomita Mall
Stanford University, Stanford, CA 94305-4045
(650) 736-2152 Fax: (650) 736-1984

References

1. Committee on Science, Engineering, and Public Policy (COSEPUP). 1997. International Benchmarking of US Mathematics Research. Washington, DC: National Academy Press.
2. Committee on Science, Engineering, and Public Policy (COSEPUP). 1998. International Benchmarking of US Materials Science and Engineering Research. Washington, DC: National Academy Press.
3. Committee on Science, Engineering, and Public Policy (COSEPUP). 1999. International Benchmarking of US Immunology Research. Washington, DC: National Academy Press.
4. Committee on Science, Engineering, and Public Policy (COSEPUP). 2000. Experiments in International Benchmarking of US Research Fields. Washington, DC: National Academy Press.
5. Committee on Science, Engineering, and Public Policy (COSEPUP). 2000. Evaluating Federal Research Programs: Research and the Government Performance and Results Act. Washington, DC: National Academy Press.
6. National Research Council (NRC). 1995. Allocating Federal Funds for Science and Technology. Washington, DC: National Academy Press.
7. United Kingdom Office of Science and Technology. 1997. The Quality of the UK Science Base. London, UK: Department of Trade and Industry. March.

Photovoltaics: Energy for the New Millennium

Thomas Surek

Introduction
Photovoltaics (PV) is a semiconductor-based technology that directly converts sunlight to electricity. The stimulus for terrestrial PV started more than 25 years ago in response to the oil crises of the 1970s resulted in major government programs in the United States, Japan, Europe, and elsewhere. Ongoing concerns with the global environment, as well as the worldwide efforts to seek alternate, local sources of energy, continue to drive the investment in PV research and deployment. Today, the manufacture, sale, and use of PV has become a billion-dollar industry worldwide, with more than 200 megawatts (MW) of PV modules shipped in 1999.
Over the past 25 years, research and development has led to the discovery of new PV materials, devices, and fabrication approaches; continuing improvements in the efficiency and reliability of solar cells and modules; and lower PV module and system costs. This article reviews the rapid progress that has occurred in PV technology from the laboratory to the marketplace, including reviews of the leading technology options, status and issues, and key industry players. Major ongoing efforts involve a better understanding of the crystal and film growth processes and the resulting material properties. New processes for fabricating PV materials and devices, and innovative PV approaches with low-cost potential are elements of an ongoing research program aimed at future improvements in PV cost and performance.

Progress, Status, and Research Directions of Photovoltaic Technologies
Photovoltaic technologies can be divided into two main areas: flat-plates and concentrators. In the flat-plate technologies, semiconductor material is used to cover as much area as possible on a flat surface, while balancing tradeoffs between material cost and conversion efficiency of light into electrical power.

Flat-plate technologies include thick cells of crystalline silicon (from both ingot and sheet-growth techniques) and thin-films. Thin-films are typically less than 100m m of material (e.g. amorphous silicon, copper indium diselenide, cadmium telluride, and polycrystalline silicon) deposited using vapor deposition, electrodeposition, or wet chemical process. Present thin-film approaches generally do not allow conversion efficiencies as high as those demonstrated by crystalline silicon modules. In spite of this, development of thin-film approaches is an active area of research, since thin-film cells require 1/10th to 1/100th the amount of expensive semiconductor material compared to that required by crystalline silicon cells with equal collection areas.

Table 1 presents cell and module conversion efficiencies (percentage of sunlight converted to electricity under standard conditions) for both ingot- and non-ingot-based crystalline silicon technologies. Although there are specific areas for improvement associated with each of the crystalline silicon sub-technologies, general research areas that apply to crystalline silicon include:

1. manufacturing yield and throughput,
2. impurity/defect gettering and passivation,
3. low-cost, high-efficiency processes,
4. environmentally benign processing and waste stream reduction,
5. manufacturing automation and module packaging for 30-year life,
6. thinner wafers or sheets and associated handling,
7. wire-saw slurry recycling (ingots only), and
8. new processes to produce "solar-grade" silicon.

Table 1. Crystalline Silicon PV Conversion Efficiencies (%)

Table 2 presents conversion efficiencies for thin-film cells and modules. Similar to crystalline silicon, increased manufacturing throughput and yield and improved conversion efficiency are primary concerns for all thin films. Special attention is directed towards reducing the gap between laboratory cell efficiencies and production module efficiencies. Specific amorphous silicon research is directed to the following areas:

1. novel growth techniques that allow higher growth rates and better materials and
2. improved fundamental understanding with the goal of improved material stability and long-term field performance.

Current cadmium telluride R&D includes work addressing the issues of:

1. improved film deposition,
2. better contacting techniques for extracting electrical power from the cells, and
3. low-cost module packaging for long-term reliability.

Current R&D areas for copper indium diselenide are:

1. scalability of production processes,
2. new deposition techniques and materials that lend themselves to lower temperature and non-vacuum approaches, and
3. improved understanding of the device physics at the active semiconductor junction.

R&D for thin-film silicon includes developing techniques for high-rate deposition of large-grain-size films on foreign substrates.

Table 2. Thin-Film PV Conversion Efficiencies (%)

Concentrator technologies are generally of two types: low concentration (typically 10 to 40 suns) which uses line or one-dimensional focus, and high concentration (typically 100 to 1000 suns) which uses point or two-dimensional focus. In addition to balancing material cost and conversion efficiency, portions of the more expensive semiconductor material in flat-plate systems are replaced with a system of lenses or reflectors that can be made from less expensive materials. This replacement may, however, be at the expense of overall system efficiency, and thus one should consider each system as a whole in evaluating its benefits.

Table 3 presents solar conversion efficiencies for various materials that lend themselves well to the somewhat higher module operating temperatures often found in concentrator systems. Note that the efficiencies are reported at particular concentration ratios since the efficiencies are a function of measurement conditions, including light intensity. Module efficiencies are in the range of 15% to 17 % for silicon-based systems, with prototypes of more than 20%. Modules using GaAs cells have efficiencies of more than 24%. A prototype module with a three-junction GaInP2/GaAs/Ge cell measured at 28% efficiency (10 suns).

Table 3. Cell Efficiencies for Concentrator PV Systems (%)

General issues for concentrator systems include the structural characteristics of the system that lend themselves to larger applications and make the highly visible and currently more-prevalent small-application market less useful to concentrators in terms of establishing market position. An additional concern is that concentrator systems use essentially only direct radiation, and therefore their areas of best application require high-intensity sunlight, such as the southwest United States. Areas of R&D that are important for concentrators include, as in flat-plate PV, manufacturing yield and throughput and higher conversion efficiency to reduce ultimate energy cost. Higher efficiencies are expected from multijunction structures, including 3- and 4-junction devices. Novel concentrating techniques may also ultimately be incorporated into successful concentrator systems.

Markets and Applications
Photovoltaic systems may be used for almost any situation requiring electrical power, either tied to or independent of the utility grid. Systems may include energy storage and power conditioning to convert from DC to AC power. The size of the application may vary from milliwatts (as in calculators) to kilowatts (as in grid-tied, roof-mounted systems) to megawatts and larger (as envisioned with central-station generating systems). Consequently, the list of applications is long and includes developing country applications such as lighting, water pumping, health clinics, and village power; U.S. rural applications such as electric fences, water pumping for livestock, and irrigation; remote applications such as telecommunications and signaling; and grid-connected power generation on commercial and residential buildings.

Conclusions
While major market opportunities continue to exist in developing countries, where sizable populations are without any electricity, today's manufacturing expansions are fueled by market initiatives for grid-connected PV in residential and commercial buildings. The combinations of increased production capacities, with the attendant cost reductions as a result of economies of scale, are expected to lead to sustainable markets. A key to achieving the ultimate potential of PV is to continue to increase the sunlight-to-electricity conversion efficiencies and translate the laboratory successes to cost-competitive products. Building a robust technology base is essential to overcoming the perceived high-risk transition into grid-connected PV. Such a base will make PV a globally significant contribution to our energy supply and environment.

Thomas Surek
National Renewable Energy Laboratory
1617 Cole Boulevard, Golden, Colorado 80401, U.S.A.

References:

1. "Photovoltaics: Energy for the New Millenium, The National Photovoltaics Program Plan, 2000-2004," DOE/GO-10099-940 (January 2000).
2. "Terrestrial Photovoltaic Technologies -- Recent Progress in manufacturing R&D", C. E. Witt, T. Surek, et al., Proceedings of the 34th Heat Transfer Conference (August 2000).