Inhomogeneous nitrogen incorporation effects on the transport properties of GaAsN grown by CBE

Abstract

In this paper, the Chemical Beam Epitaxy approach to GaAsN material growth has been investigated. Photoluminescence and Hall effect measurements were performed to clarify the influence of defects on the transport properties, those of holes in particular. The PL intensity of near-band emission (1.35eV-peak) for GaAs0.996N0.004 at low temperature (<100K) can be well fitted by considering the effects of N-related localized states, whilst the PL intensity was followed an Arrhenius dependence in the temperature region higher than 150K. It was concluded that the formation of N-related localized states, arising from the alloy disorder (N clusters), still cannot be avoided in GaAsN deposited by CBE. To further study its effects on the transport properties, we have also studied the contribution of various alloy scattering mechanisms to the temperature dependence of Hall mobility. The alloy scattering coefficient KAlloy-1 was calculated from the fitting of an alloy scattering mechanism. In addition, a pseudo-alloy scattering coefficient KAlloy-2 was theoretical deduced by assuming the nitrogen atoms were homogeneously incorporated along the growth direction. The ratio of those two values was studied: the departure from 1 (KAlloy-2−1/KAlloy-1−1>1) indicated that the N atoms were alloyed in a disordered arrangement. As a result, the corresponding alloy scattering mechanism was enhanced, contributing to the hole mobility decrease. However, compared to p-type GaAsN grown by MBE or MOCVD, our CBE-grown GaAsN showed a higher value of hole mobility.