Study of the influence of strained superlattices introduced into a metamorphic buffer on the electrophysical properties and the atomic structure of InAlAs/InGaAs MHEMT heterostructures

The results of studying the influence of strained superlattices introduced into a metamorphic buffer on the electrophysical properties and atomic crystal structure of In$_{0.70}$Al$_{0.30}$As/In$_{0.76}$Ga$_{0.24}$As/In$_{0.70}$Al$_{0.30}$As metamorphic high-electron-mobility transistor (MHEMT) nanoheterostructures on GaAs substrates are presented. Two types of MHEMT structures are grown by molecular beam epitaxy, namely, one with a linear increase in $x$ in the In$_x$Al$_{1-x}$As metamorphic buffer, and the second with two mismatched superlattices introduced inside the metamorphic buffer. The electrophysical and structural parameters of the grown samples are studied by the van der Pauw method, transmission electron microscopy (including scanning and high-resolution microscopy), atomic-force microscopy, and energy dispersive X-ray analysis. It is revealed that the introduction of superlattices into a metamorphic buffer substantially improves the electrophysical and structural characteristics of MHEMT structures.