Al/ZnO/a-SiGe:H: a system protected by the ZnO buffer from metal-induced crystallization

摘要

Metal-Induced-Crystallization (MIC) by teh contact of amorphous semiconductors with metals is one of the4 degradation factors in solar cells.This study has been made on the barrier properties of a ZnO layer between undoped-a-SiGe:H and Al metallization films in the structure (001)Si/SiO-2/a-SiGe:H/ZnO/Al. Plasma assisted CVD deposition was used to produce a-Si_1-xGe_x:H (x=1to1) undoped films over thermally oxidized Si-=wafers.There were covered with 500 A and 1000A thick transparent conductive layers of ZnO:Al and then 1000A thick films of Al.A set of Al-implanted a-Si, a-Ge, and a-Si_0.5Ge_0.5 films on Si/SiO_2 substrates was also prepared to study MIC in an amorphous system with dispersed Al.The structures were annealed in vacuum in the temperature range of 200 deg C to 400 deg C for 1h,X-ray diffraction studies demonstrated the a-SiGe:H stability against crystallization under ZnO protection up to 400 deg C.Secondary Ion mass Spectroscopy didn's reveal any noticeable redistribution of Al inside Al-implanted a-Si:H and a-Si_0.5Ge_0.5:H samples after annealing at 500 deg C for 1h, but strong Al diffusion was seen in the a-Ge:H layer, Nevertheless.no MIC was observed in any of the Al-implanted a-materials.