EFFECT OF BORON DOPING ON THE STRUCTURAL-PROPERTIES OF POLYCRYSTALLINE SILICON FILMS GROWN AT REDUCED PRESSURES

Abstract

The deposition and properties of in situ boron-doped polycrystalline silicon (poly-Si) films grown at 550-degrees-C were investigated using an ultrahigh vacuum chemical vapor deposition system. It is observed that, if the doping level is high enough, the boron incorporation would significantly reduce the deposition rate, impede the grain growth, and degrade the crystallinity of the poly-Si films. We also found that the preferential adsorption of boron atoms on the SiO2 surface at the initial stage of deposition shortened the incubation time of deposition. The property of trapping states at the grain boundary is also examined, and a density of about 4.7 X 10(12) CM-2 is obtained for poly-Si films with a doping level less than 2.2 X 10(19) cm-3.