Structural and electrophysical properties of In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As/InP HEMT nanoheterostructures with different combinations of InAs and GaAs inserts in quantum well

摘要

A complex investigation of structural and electrical properties of In0.52Al0.48As/In (y) Ga1 - y As/In0.52Al0.48As nanoheterostructures on InP substrates containing thin InAs and GaAs inserts in a quantum well (QW) has been performed. The GaAs nanolayers are grown at the QW boundaries between InGaAs and InAlAs layers, while the double InAs inserts are grown in InGaAs layers symmetrically with respect to the QW center. The layer and interface structures have been studied by transmission electron microscopy. It is shown that, when using the proposed epitaxial growth conditions, the introduction of 1.2-nm-thick InAs nanoinserts into the InGaAs QW and a 1-nm-thick GaAs nanobarrier at the QW boundaries does not induce structural defects. The diffusion of the InAlAs/InGaAs interface (2-3 monolayers) and InAs/InGaAs nanoinsert interface (1-2 monolayers) has been estimated. Measured Hall mobilities and electron concentrations in structures with different combinations of InAs and GaAs inserts have been analyzed using calculated energy band diagrams and electron density distributions. It is found that the photoluminescence spectra of the structures under study have differences caused by specific structural features of coupled QWs (specifically, the change in the In molar fraction due to InAs inserts and the change in the QW thickness due to GaAs transition barriers.