Atomic relocation of fast diffusers in impurity-free disordered p-type GaAs

We have used deep level transient spectroscopy (DLTS) and capacitance-voltage (C-V) measurements to study impurity free disordering (IFD) of p-type GaAs epitaxial layers grown by metal-organic chemical vapour deposition (MOCVD). Disordering was achieved using either an SiO₂ or native oxide layer of the same thickness. Samples, including an uncapped layer for reference, were annealed at 900°C for 30 s under an Ar ambient. Impurity-free disordering resulted in an increase in the free hole concentration, with the effect being most pronounced when using the SiO₂ capping layer. DLTS measurements revealed a corresponding increase in the concentrations of both Cu- and Zn-related deep levels in disordered epilayers. The results presented here will be discussed in terms of the atomic relocation processes that take place during the nonequilibrium injection of excess gallium vacancies into the disordered p-type epilayers.