P+ polycrystalline silicon growth via hot wire chemical vapour deposition for silicon solar cells

Abstract

Hot wire chemical vapour deposition (HWCVD) is explored as a way of growing boron-doped silicon for photovoltaic devices. Deposition temperatures are measured using a custom-built monitoring system for two different filament configurations within the HWCVD tool. A refined fabrication process is presented, using an altered filament arrangement, that currently provides a maximum deposition temperature of 535 °C, for growing boron-doped silicon films via HWCVD, with the inclusion of a short post-deposition anneal at 800 °C for 2 min. Transmission electron microscopy reveals improvements in interfacial quality, as well as larger grains, present after post-annealing treatments. In addition, re-crystallisation of as-deposited amorphous Si films under a short anneal is confirmed using Raman spectroscopy. The enhancements in morphology translate to a boost in current rectification based on dark current-voltage measurements. This is further supported by secondary-ion mass spectrometry analysis, presenting p+ properties with uniform doping in the 1021 cm−3 region.