Defects and transport in a-Si : H/c-Si heterojunctions

We have investigated amorphous silicon/crystalline silicon np and pn hetero junction devices with transport and capacitance measurement techniques. The devices consist of doped n-type or p-type hydrogenated amorphous silicon d eposited on p-type or n-type float-zone crystalline silicon wafers. Low tem perature (100 It) photocurrent measurements in conjunction with numerical s imulations indicate a large conduction band offset at the interface between the two materials. We show experimentally and with numerical simulation th at defects at the heterojunction interface affect the low frequency capacit ance and the electronic transport in the devices. (C) 2000 Published by Els evier Science B.V. All rights reserved.