Communication Research

Contains reports on five research projects.Rand Corporatio

Crystalline-silicon photovoltaics: Necessary and sufficient

Photovoltaic (PV) energy systems have always been dominated by crystalline-silicon (c-Si) technology, and recent developments persuasively suggest that c-Si will continue to be the dominant technology well into the next century. The authors explain why c-Si technology is fairing much better than previously expected, and discuss the impact of improvements currently under development. They use a ground-up, engineering-based approach to predict the expected evolution of this type of PV system, and argue that c-Si PV will be in a position to compete for the US residential power market starting in about the year 2010. This market alone will provide the opportunity for PV to supply several percent of the electrical energy used in the United States. Crystalline-silicon technology is therefore not just necessary for building a near-term PV industry; it also offers a low-risk approach to meeting long-term goals for PV energy systems

Extraction of the surface recombination velocity of passivated phosphorus-doped silicon emitters

An analytical procedure to extract the surface recombination velocity of the SiO{sub 2}/n type silicon interface, S{sub p}, from PCD measurements of emitter recombination currents is described. The analysis shows that the extracted values of S{sub p} are significantly affected by the assumed material parameters for highly doped silicon, t{sub p}, {mu}{sub p} and {Delta}E{sub g}{sup app}. Updated values for these parameters are used to obtain the dependence of S{sub p} on the phosphorus concentration, N{sub D}, using both previous and new experimental data. The new evidence supports the finding that S{sub p} increases strongly with N{sub D}

Process development for high-efficiency silicon solar cells

Fabrication of high-efficiency silicon solar cells in an industrial environment requires a different optimization than in a laboratory environment. Strategies are presented for process development of high-efficiency silicon solar cells, with a goal of simplifying technology transfer into an industrial setting. The strategies emphasize the use of statistical experimental design for process optimization, and the use of baseline processes and cells for process monitoring and quality control. 8 refs

Processing Experiments for Development of High-Efficiency Silicon Solar Cells

Fabrication of high-efficiency silicon solar cells requires processing technology capable of maintaining long bulk carrier lifetime and low surface recombination. Development of long-lifetime processing techniques using experimental designs based on statistical methods is described. The first three experiments investigated pre-oxidation cleans, phosphorus gettering, and a comparison of different phosphorus diffusion sources. Optimal processing parameters were found to depend on type of silicon material. 2 refs., 2 figs., 2 tabs