Effects of Residual Carbon and Hydrogen Atoms on Electrical Property of GaAsN Films Grown by Chemical Beam Epitaxy

Abstract

The electrical behavior of nitrogen–hydrogen (N–H) complexes and carbon (C) atoms in GaAsN films grown by the chemical beam epitaxy (CBE) method have been studied by comparing H concentrations and hole concentrations. The contributions of H and C concentrations ([H] and [C]) to ionized impurity scattering have been also investigated. In the GaAsN films, there were three acceptor levels (A0, A1, and A2). The energy levels of A1 and A2 were 130 and 55 meV, respectively. The concentration of the deepest acceptor (A0) was more than 1019 cm-3, which was higher than [H] and [C]. A2 was observed only in films with a high [C]. The amount of A1 was proportional to [H]. Most of the residual H formed N–H complexes; thus, it is concluded that the N–H complex behaved as an acceptor in GaAsN films. At low temperatures, ionized impurity scattering limited the total hole mobility. The inverse numbers of the coefficients for the ionized scattering were consistent with [C] instead of [H]. This suggests that all the residual C atoms were ionized owing to compensation by the donors. A disagreement between N composition and alloy scattering has been also detected. This might indicate a fluctuation in the N composition in the GaAsN films.