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JOURNALS // Fizika i Tekhnika Poluprovodnikov // Archive

Fizika i Tekhnika Poluprovodnikov, 2023 Volume 57, Issue 3, Pages 153–159 (Mi phts6850)

Surface, interfaces, thin films

Reduction of misfit dislocation density in metamorphic heterostructures by design optimization of the buffer layer with non-linear graded composition profile

M. Yu. Chernov, V. A. Solov'ev, S. V. Ivanov

Ioffe Institute, St. Petersburg, Russia

Abstract: Equilibrium distributions of misfit dislocation density along the growth direction of metamorphic buffer layers In$_x$Al$_{1-x}$As/GaAs with maximum In content $x_{\mathrm{max}}\ge$ 0.77 and different non-linear graded composition profiles $x\varpropto z^{1/n}$ are calculated. The effect of the initial In composition ($n$ = 2) of In$_x$Al$_{1-x}$As buffer layer with convex-graded $(x_{\mathrm{min}})$ composition profile on misfit dislocation density as well as amount of residual stresses at its top part is considered. Using computational approach, it was shown that a dislocation-free region is formed under thin tensile-strained GaAs layer (1–10 nm) inserted into InAlAs metamorphic buffer layer, which agrees with experimental data obtained early by transmission electron microscopy. Novel non-linear graded composition profile of metamorphic buffer layer has been proposed, which results in twice reduction of misfit dislocation density as compared to the convex-graded one. In addition, equilibrium distributions of misfit dislocation density in the HEMT heterostructures with two-dimensional electron channel In$_x$Al$_{1-x}$As, which are based on In$_x$Al$_{1-x}$As/GaAs metamorphic buffer layer of various designs, are calculated. The values of inverse steps $(\Delta)$, representing the difference between the maximum In content of In$_x$Al$_{1-x}$As $(x_{\mathrm{max}})$ and In content of In$_{0.75}$Ga$_{0.25}$As virtual substrate, at which relaxation of the elastic strains in 2D channel In$_{0.75}$Ga$_{0.25}$As/In$_{0.75}$Al$_{0.25}$As doesn't occur, are calculated for metamorphic buffer layers In$_x$Al$_{1-x}$As with convex-graded and optimized non-linear graded composition profiles.

Keywords: metamorphic heterostructures, metamorphic buffer layer, misfit dislocations, elastic stresses, In(Ga,Al)As/GaAs.

Received: 26.04.2023
Revised: 02.05.2023
Accepted: 02.05.2023

DOI: 10.21883/FTP.2023.03.55627.4915



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© Steklov Math. Inst. of RAS, 2025