Effect of Si doping on the relaxation mechanism of InGaAs on GaAs

Abstract

We report measurements on the initial stages of relaxation of Si-doped In0.04Ga0.96As epitaxial layers on (001) GaAs using in situ high-resolution double-crystal x-ray topography during molecular beam epitaxial growth. For Si concentrations up to 5×1018 cm−3, the critical thickness for formation of the first B(g) misfit dislocations is modeled accurately by the Matthews–Blakeslee model, extended to include a lattice friction force varying linearly with the dopant concentration. Below a Si concentration of 2×1018 cm−3, the model can be used to predict the critical thickness for generation of the orthogonal A(g) dislocation set, with the x-ray topographs showing that the B(g) misfit multiplication occurs at damaged edges of the wafer. However, above 2×1018 cm−3 Si concentration, the critical thickness for A(g) nucleation becomes almost independent of concentration and the x-ray topographs show that cross slip becomes important in the multiplication process. For most of the Si concentrations examined, the critical thickness for nucleation of the slow A(g) misfit dislocations corresponded to that of multiplication of the fast B(g) set.

Crosshatch observation in MBE-grown Be-doped InGaAs epilayer on InP

“…Thus, Be-doping is more effective in increasing the critical thickness of In x Ga 1Àx As than Sidoping. According to the explanation of Tanner et al [1,2], those results indicate that the frictional force for Be-doping is larger than that for Sidoping.…”

“…It is seen that dislocations are confined at and within 100 nm above the interface between the In 0.77-Ga 0.23 As bulk-like thin film and the In 0.52 Al 0.48 As buffer layer. On the other hand, the crosshatch patterns were observed on the surfaces of Si-doped ([Si] ¼ 0-5 Â 10 18 cm À3 ) In 0.04 Ga 0.96 As grown on GaAs at the layer thickness of more than 200 nm [1,2]. Thus, Be-doping is more effective in increasing the critical thickness of In x Ga 1Àx As than Sidoping.…”

“…To overcome this difficulty, impurity doping effect was investigated on In 0.04 Ga 0.96 As films grown on GaAs substrate by using Si donor atoms, the result of which shows a limited success that Si doping up to 5 Â 10 18 cm À3 is useful to increase the critical thickness by a factor of two from 100 to 200 nm. This effect was accounted for in terms of the Peierls stress [1,2]. Nevertheless, thicker films are still very difficult to grow.…”

Investigation of the anisotropic strain relaxation in GaSb islands on GaP

“…38,39 Thus, the V-core glide set and III-core glide set dislocation should be the highest density 60 dislocations during the observations. Moreover, the V-core glide set (a type) 60 dislocations have been shown to have a lower formation energy and higher glide velocity, 37,38,40 in comparison with III-core (b type).…”