Effect of (1 0 0) GaAs substrate misorientation on electrophysical parameters, structural properties and surface morphology of metamorphic HEMT nanoheterostructures InGaAs/InAlAs

Abstract

The effect of GaAs (100) substrate misorientation on metamorphic high electron mobility transistor nanoheterostructure In0.64Al0.3As/In0.7Ga0.3As properties was studied by the means of Hall measurements, photoluminescence spectroscopy, X-ray diffraction, TEM and STEM measurements. The identical heterostructures with step-graded metamorphic buffer InAlAs were grown by MBE on (100) GaAs substrates exactly oriented and 2° misoriented towards [0−1−1] direction and the detailed comparison of electronic and structural properties was performed. The increase of electron density by 40% was found in the heterostructure grown on misoriented GaAs substrate though Si doping concentration in δ-layers was the same for both samples. In addition the substrate misorientation affected some of the heterostructure structural properties: the QW heterointerfaces were found to be more broadened, the residual strain in the In0.64Al0.36As barrier region was higher and the surface morphology was rougher in the heterostructure on (100)+2° substrate as compared to that on the (100) GaAs substrate.