Advanced deposition phase diagrams for guiding Si:H-based multijunction solar cells

Phase diagrams have been established to describe very high frequency (vhf) plasma-enhanced chemical vapor deposition (PECVD) of intrinsic hydrogenated silicon (Si:H) and silicon–germanium alloy (Si1−xGex:H) thin films on crystalline Si substrates that have been over-deposited with n-type amorphous Si:H (a-Si:H). The Si:H and Si1−xGex:H films are prepared under conditions used for the top and middle i-layers of high efficiency triple-junction a-Si:H-based n–i–p solar cells. Identical n/i cell structures were co-deposited in this study on textured (stainless steel)/Ag/ZnO which serve as substrate/back-reflectors in order to relate the phase diagrams to the performance parameters of single-junction solar cells. This study has reaffirmed that the highest efficiencies for a-Si:H and a-Si1−xGex:H solar cells are obtained when the i-layers are prepared under previously-described maximal H2 dilution conditions.