A study of single chamber RF-PECVD /spl mu/c-Si solar cells

We report on a study of p-i-n type single junction solar cells with microcrystalline silicon (/spl mu/c-Si:H) i-layers, deposited entirely in a single chamber, batch-process type RF-PECVD system without load-lock, using the hydrogen dilution method. Conversion efficiency of 5% has been obtained on inexpensive, commercial SnO/sub 2/-coated, 3-mm thick soda-lime glass substrates, using Al back contact without efficient back reflector. The most critical process step is the seeding procedure by which /spl mu/c-Si:H absorber(the i-layer) is grown over amorphous-Si under-layers. Seeding by boron-doped p-layer leads to superior devices of excellent stability than seeding inside i-layer. A great challenge is the pronounced non-uniformity of /spl mu/c-Si:H solar cells. Single chamber operation issues with cross-contamination and process gas purity are discussed.