No abstract

W e report the investigation of impurity-induced disordering (110) in strained In,Ga, -,As/GaAs ( x = 0.21-0.24) single quantum well (ow) heterostructures using a two-stage Zn diffusion and thermal annealing process. The samples were grown by MOVPE, and different shallow Zn diffusion depths were allowed in the GaAs cap layer in order to vary the Zn concentration in t h e ow. Thermal annealing of the samples at 785 "C for 10 min under an AsHJH, atmosphere then created 110. Both partially disordered and completely disordered ow heterostructures were studied. The In-Ga interdiffusion was monitored by the photoluminescence (PL) spectroscopy of the ground state emission from the aw. The interdiffusion coefficients were determined by adjusting t h e data calculated by using the envelope function approximation with the shifts of the PL peak position after the annealing. T h e interdiffusion coefficient is found to be very strongly dependent on the Zn diffusion depth, and consequently on the Zn concentration in t h e ow layer, Finally, we propose a model that involves an interstitial migration process in order to explain t h e enhancement of In-Ga interdiffusion by Zn diffusion '

We have undertaken electrochemical C-V measurements of Ga0.94Al0.06As:Ga0.57Al0.43As isotype n-n heterojunctions in order to determine the conduction band offset ΔEc. Samples were grown by liquid-phase epitaxy; carrier concentrations were determined to be, respectively, 1016 cm−3 for the small band-gap layer and 1016 cm−3 or 1017 cm−3 for the large band-gap layer. From results obtained with various different samples, we determine ΔEc/ΔEg≊0.54–0.64, quite close to the new accepted value of the GaAs:GaAlAs interface. Moreover, the density of fixed interface charges are estimated and found to be related to the monolayer doping density of the large band-gap layer.

No abstract