Deposition of P-Type Nanocrystalline Silicon Using High Pressure in a VHF-PECVD Single Chamber System

Abstract

In this article, we present a study of boron-doped hydrogenated nanocrystalline silicon (nc-Si: H) films by very high frequency-plasma enhanced chemical vapor deposition (VHF-PECVD) using high deposition pressure. Electrical, structural and optical properties of the films were investigated. Dark conductivity as high as 2.75S/cm of p-type nc-Si: H prepared at 2.5Torr pressure has been achieved at a deposition rate of 1.75Å/s for 25nm thin film. By controlling boron and phosphorus contamination, single junction nc-Si: H solar cells incorporated p-layers prepared under high pressure and low pressure, respectively, were deposited. It has been proven that nanocrystalline silicon solar cells with incorporation of p layer prepared at high pressure has resulted in enhanced open circuit voltage, short circuit current density and subsequently high conversion efficiency. Through the optimization of the bottom solar cell and application of ZnO/Al back reflector, 10.59% initial conversion efficiency of micromorph tandem solar cell (1.027cm2) with an open circuit voltage of 1.3864V, has been fabricated, where the bottom solar cell using a high pressure p layer was deposited in a single chamber.