Comprehensive investigation of the interfacial misfit array formation in GaSb/GaAs material system

Abstract

A comprehensive investigation of the interfacial misfit (IMF) array formation has been carried out. The studies were based on the static phase diagram for GaAs (001) surface and As2 dimers on the surface. Prior to the initiation of the GaSb growth two attempts of the temperature decreasing were performed: before and after the GaAs termination. The GaAs was grown in the optimal conditions for GaSb material. The influence of the interruption time on GaSb/GaAs heterostructure parameters was examined. Two cases were investigated: with and without Sb-soaking of the GaAs surface. The periodic array of edge dislocations at GaSb/GaAs interface was confirmed using Burger’s circuit theory. Careful examination of misfit surroundings revealed one uncompleted Burger’s vector that indicated one dislocation of mixed type among eight of the edge type. The distance between lattice sites of dislocations was 5.51 nm on average. The crystal quality of 5.0 µm GaSb layer was characterized by FWHM2θ/ω = 42 arcsec, FWHMRC = 125 arcsec. The EPD = 4 × 106 cm− 2 was estimated after etching in FeCl3:HCl solution. The Δqz/Δqx ratio of 0.60 for 5.0 µm GaSb layer was higher than for 2.5 µm GaSb layer of 0.59. The probable reason was the thickness-dependent 60° dislocation density. The electrical parameters measured for 2.5 µm GaSb were: p = 4.0 × 1016cm−3 (2.0 × 1016cm−3) and µ = 599 cm2/V s (3420 cm2/V s) at 300 K (77 K).