Origin of Boron Contamination of the Intrinsic Amorphous Silicon Hydrogen Alloys in Glow Discharge System

Abstract

Boron contamination of the intrinsic amorphous silicon hydrogen alloys deposited in a single chamber system using both low (29 kHz) and high (10 MHz) frequency glow discharge has been studied in detail. The contamination process was simulated by flowing the p‐type deposition gas through the system with or without turning on the plasma. Several methods were applied to reduce the contamination and their effects were investigated by measuring the change of the light conductivity and the activation energy of the contaminated i layer. A model that emphasizes the role of plasma in the contamination processes was proposed to explain the observed results. It was found that when using low frequency plasma deposition a dummy cathode method and “soft” deposition of a thin a‐Si:H can be applied to reduce the boron contamination problem.