Mutual passivation effects in Si-doped diluted InyGa 1-yAs1-xNx alloys

We report systematic investigations of the mutual passivation effects of Si hydrogenic donors and isovalent nitrogen in dilute InGaAs_1-xN _x alloys. Upon thermal annealing at temperatures above ∼650 °C, the Si atoms diffuse assisted by the formation and migration of Ga vacancies. When they find nitrogen atoms, they form stable Si _Ga-N_As nearest-neighbor pairs. As a result of the pair formation, the electrical activity of Si_Ga donors is passivated. At the same time, the effect of an equal number of N_As atoms is also deactivated. The passivation of the shallow donors and the N_As atoms is manifested in a drastic reduction in the free electron concentration and, simultaneously, an increase in the fundamental band gap. Analytical calculations of the passivation process based on Ga vacancies mediated diffusion show good agreement with the experimental results. Monte Carlo simulations have also been performed for a comparison with these results. The effects of mutual passivation on the mobility of free electrons are quantitatively explained on the basis of the band anticrossing model. Optical properties of annealed Si-doped InGaAs_1-xN_x samples are also discussed.