Mutual Passivation of Group IV Donors and Isovalent Nitrogen in Diluted GaN x As 1-x Alloys

Abstract

We demonstrate the mutual passivation of electrically active group IV donors and isovalent N atoms in the GaNxAs1-x alloy system. This phenomenon occurs through the formation of a donor-nitrogen bond in the nearest neighbor IVGa-NAs pairs. In Si-doped GaInN0.017As0.983 the electron concentration starts to decrease rapidly at an annealing temperature of 700°C from ∼ 3 × 1019cm-3 in the as-grown state to less than 10 16cm-3 after an annealing at 900°C for 10s. At the same time, annealing of this sample at 950°C increases the gap by about 35 meV, corresponding to a reduction of the concentration of the active N atoms by an amount very close to the total Si concentration. We also show that the formation of SiGa-NAs pairs is controlled by the diffusion of Si via Ga vacancies to the nearest NAs site. The general nature of this mutual passivation effect is confirmed by our study of Ge-doped GaNxAs1-x layers formed by N and Ge co-implantation in GaAs followed by pulsed laser melting. Published by Elsevier B.V.