Relative importance of deposition rate for surface potential in amorphous silicon/SiO2 interface

Abstract

Hydrogenated amorphous silicon (a-Si:H)-based metal oxide semiconductor (MOS) structures were prepared with various deposition conditions. A-Si:H films were deposited by reactive sputtering method with different substrate temperatures, hydrogen partial pressures and argon-helium gas mixture. The surface potential at the interface a-Si:H/oxide was deduced from MOS current density-voltage characteristic and a-Si:H film dark conductivity activation energy. The correlation between the deposition rate, the surface potential and their respective variation with deposition parameters indicates the clear evidence of the deposition rate influence on a-Si:H/insulator interface quality; this is explained in terms of film growth mechanism. We have concluded that the interface states are due to the silicon dangling bonds and are mostly negatively charged.