The influence of hydrogen passivation of silicon on the photocurrent of CdS/Si heterodiodes

A CdS/p-Si:H heterojunction is formed by the evaporation of CdS on a hydrog en passivated Si wafer. It is found that the substrate passivation procedur e has a strong influence on the photocurrent properties of the CdS/p-Si int erface. In fact, in addition to the photoresponse in the red and infrared s pectral ranges, the CdS/p-Si:H heterodiode also reveals photocurrent in the blue and green. This is in contrast to CdS/p-Si and CdS/p-InP devices, whi ch do not exhibit photocurrent in the absorption region of CdS. The positiv e influence of the passivation on the optoelectronic properties of the CdS/ p-Si:H heterodiode is explained by the prevention of interface reactions du ring the formation of the device. The dependence of the photocurrent of the CdS/p-Si:H heterodiode on an applied bias gives evidence of a homojunction -like behavior. (C) 1999 Published by Elsevier Science S.A. All rights rese rved.