Semiconductor basic body for solar cell - has high ohmic emitter, applied covering layer and light-sensitive top surface having several laser-produced notches with second low ohmic emitter diffused only into notch area

摘要

The cover layer (2) partic. of silicom dioxide comprises three individual layers, the lower of which serves to render passive the semiconductor top surface. Its middle layer (2b) is formed as an anti-reflection layer, whilst its upper layer (2c) is for protective purposes. The lower layer (2a) can be of SiO2 or SiC., and have a thickness of approximately 5 to 30 nm. The middle, reflection-reducing layer (2b) can be of TiOx,Si3N4, or Ta2O5, and is approximately 70 nm thick. The upper layer (2c) is of SiO2, and has a refraction index close to the embedded material of solar cells, i.e. approximately 1.5. It is optically inactive after the embedding of the solar cell. The lower and middle layers can be replaced by an intermediate layer which renders passive the top surface of the solar cells and also acts as an anti-reflection layer. ADVANTAGE - As cover layer for semiconductor basic body which after embedding of solar cell has optimal reflection-reducing properties.