A study and control of lattice sites of N and In/Ga interdiffusion in dilute nitride quantum wells

摘要

We studied effects of the distribution of interstitial (N_i) and substitutional nitrogen (N_s) and In/Ga interdiffusion on optical properties of the dilute nitride quantum wells (QWs) and the ways of suppressing diffusion. Without annealing, the concentration of N_i remained almost constant while N_s was linearly dependent on the total number of N. After annealing, the N_i can be removed dramatically, and interdiffusion between In and Ga was found. Inserting a thin In_(xd)Ga_(1-xd)N_(yd)As_(1-yd) layer on either side of an In_(xq)Ga_(1-xq)N_(yq)As_(1-yq) QW (xq>xd) appears to suppress this interdiffusion. As a consequence, a blue shift of the photoluminescence signal after annealing remained small and the optical activity was largely improved. It was also found that a small amount of N incorporated in InGaAs QWs embedded in GaAs increased the In/Ga interdiffusion and that increased mechanical stresses enhanced the interdiffusion.