Absence of oxygen diffusion during hydrogen passivation of shallow-acceptor impurities in single-crystal silicon

Abstract

It was recently proposed that hydrogen compensation of shallow-acceptor impurities in single-crystal silicon is due to the diffusion of both monatomic oxygen and hydrogen into silicon which combine at acceptor sites to form neutral acceptor-OH complexes. It is shown here that oxygen does not diffuse into silicon under the conditions of shallow-acceptor passivation. Boron-doped silicon was exposed to monatomic deuterium and mass 18 oxygen at elevated temperatures. Depth profiles of D and 18O were measured by secondary-ion mass spectrometry for comparison with the boron concentration. While D readily diffuses into silicon with the concentration nearly equal to that of the boron, no 18O was detectable above the background level. Deuterium profiles in both phosphorus-doped and boron-doped silicon further reveal high densities of deuterium, in excess of the boron concentration, which are ascribed to diffusing monatomic deuterium and deuterium that is immobilized through recombination and impurity trapping.