Effect of Te doping of InGaAsSb layers on the interface quality of InGaAsSb/GaSb heterojunctions

Using the liquid phase epitaxy technique we have grown quaternary p-type Ga_0.84In_0.16As_0.14Sb_0.86 layers on n-type GaSb substrates (p-N), as well as n-type layers on p-type substrates (n-P). It has been known that doping with tellurium to obtain n-type InGaAsSb layers, has important effects on the quality of the interface at the heterojunction epitaxial layer/substrate, because of the high diffusion coefficient of the Te atoms. In this work, we have applied the photoacoustic technique to measure the interface recombination velocity in both types of samples: p-N and n-P heterojunctions, and we have compared these results with measurements of atomic force microscopy made along the cross section of the interface substrate-epitaxial layer. Results from both techniques show that there is a better interface quality for the p-N heterojunction as compared to those for the N-p interfaces. The discussion of this behaviour is presented in terms of the behaviour of Te diffusion during the growth of the InGaAsSb epitaxial layers.