Analytical Model For The Optical Functions Of Amorphous Semiconductors From The Near-Infrared To Ultraviolet: Applications In Thin Film Photovoltaics, A. S. Ferlauto, G. M. Ferreira, Joshua M. Pearce, C. R. Wronski, R. W. Collins, Xunming Deng, Gautam Ganguly
Aug 2002
Analytical Model For The Optical Functions Of Amorphous Semiconductors From The Near-Infrared To Ultraviolet: Applications In Thin Film Photovoltaics, A. S. Ferlauto, G. M. Ferreira, Joshua M. Pearce, C. R. Wronski, R. W. Collins, Xunming Deng, Gautam Ganguly
Joshua M. Pearce
We have developed a Kramers–Kronig consistent analytical expression to fit the measured optical functions of hydrogenated amorphous silicon(a-Si:H) based alloys, i.e., the real and imaginary parts of the dielectric function(ε1,ε2) (or the index of refractionn and absorption coefficient α) versus photon energy E for the alloys. The alloys of interest include amorphous silicon–germanium (a-Si1−xGex:H) and silicon–carbon (a-Si1−xCx:H), with band gaps ranging continuously from ∼1.30 to 1.95 eV. The analytical expression incorporates the minimum number of physically meaningful, E independent parameters required to fit (ε1,ε2) versus E. The fit is performed simultaneously throughout the following three regions: (i) the below-band gap …
Maximization Of The Open Circuit Voltage For Hydrogenated Amorphous Silicon N–I–P Solar Cells By Incorporation Of Protocrystalline Silicon P-Type Layers, R. J. Koval, Chi Chen, G. M. Ferreira, A. S. Ferlauto, Joshua M. Pearce, P. I. Rovira, C. R. Wronski, R. W. Collins
Aug 2002
Maximization Of The Open Circuit Voltage For Hydrogenated Amorphous Silicon N–I–P Solar Cells By Incorporation Of Protocrystalline Silicon P-Type Layers, R. J. Koval, Chi Chen, G. M. Ferreira, A. S. Ferlauto, Joshua M. Pearce, P. I. Rovira, C. R. Wronski, R. W. Collins
Joshua M. Pearce
In studies of hydrogenated amorphous silicon(a-Si:H) n–i–psolar cells fabricated by rf plasma-enhanced chemical vapor deposition (PECVD), we have found that the maximum open circuit voltage (Voc) is obtained by incorporating p-type doped Si:H layers that are protocrystalline in nature. Specifically, these optimum p layers are prepared by PECVD in the a-Si:H growth regime using the maximum hydrogen-to-silane flow ratio possible without crossing the thickness-dependent transition into the mixed-phase (amorphous+microcrystalline) growth regime for the ∼200 Å p-layer thickness. The strong dependence of the p-layer phase and solar cell Voc on the underlying i-layer phase also confirms the protocrystalline nature of the …
Photovoltaics — A Path To Sustainable Futures, Joshua M. Pearce
Apr 2002
Photovoltaics — A Path To Sustainable Futures, Joshua M. Pearce
Joshua M. Pearce
As both population and energy use per capita increase, modern society is approaching physical limits to its continued fossil fuel consumption. The immediate limits are set by the planet’s ability to adapt to a changing atmospheric chemical composition, not the availability of resources. In order for a future society to be sustainable while operating at or above our current standard of living a shift away from carbon based energy sources must occur. An overview of the current state of active solar (photovoltaic, PV) energy technology is provided here to outline a partial solution for the environmental problems caused by accelerating …
Mobility Gap Profiles In Si:H Intrinsic Layers Prepared By H2 Dilution Of Sih4: Effects On The Performance Of P-I-N Solar Cells, R. J. Koval, A. S. Ferlauto, Joshua M. Pearce, R. W. Collins, C. R. Wronski
Jan 2002
Mobility Gap Profiles In Si:H Intrinsic Layers Prepared By H2 Dilution Of Sih4: Effects On The Performance Of P-I-N Solar Cells, R. J. Koval, A. S. Ferlauto, Joshua M. Pearce, R. W. Collins, C. R. Wronski
Joshua M. Pearce
Insights into the growth processes and microstructural evolution for intrinsic (i) hydrogenated silicon (Si:H) films obtained from real-time spectroscopic ellipsometry (RTSE) are extended to the characterization of the optoelectronic properties of the corresponding solar cells. Numerical modeling of the J–V characteristics and their temperature dependences support the RTSE results and provide new information about the optoelectronic properties of the i-layer materials. Experimental results are presented that strongly suggest changes in the mobility gap of the i-layer materials as their microstructure evolves with thickness, further confirming the important effect of the hydrogen dilution ratio Full-size image (<1 >K) on the transitions …