TITLE

Comparative Structural Characterization of Thin AlGa N/GaN and InAlN/GaN Heterostructures Grown on Si(111), by MBE, with Variation of Buffer Thickness

AUTHOR(S)
Chowdhury, Subhra; Borisov, Boris; Chow, Peter; Biswas, Dhrubes
PUB. DATE
November 2015
SOURCE
Journal of Electronic Materials;Nov2015, Vol. 44 Issue 11, p4144
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We report growth, by plasma-assisted molecular beam epitaxy, of thin AlGaN/GaN and InAlN/GaN heterostructures on Si(111) substrate with three different buffer thickness (600, 400, and 200 nm). Successful growth by critical optimization of growth conditions was followed by comparative characterization of these heterostructures by use of high resolution x-ray diffraction (HRXRD), including reciprocal space mapping (RSM), room-temperature photoluminescence (RT-PL), and high resolution transmission electron microscopy (HRTEM). The effect of different buffer thickness on the threading dislocation (TD) density of a thin 1.5 nm AlGaN/InAlN-1.25 nm GaN-1.5 nm AlGaN/InAlN heterostructure, was also studied. Analysis revealed increasing tensile strain with decreasing buffer thickness for AlGaN-based samples; this was confirmed by the red-shift of the GaN RT-PL peak. Reduced strain in lattice-matched InAlN-based samples resulted in a blue-shift of the GaN RT-PL peak; this was indicative of better crystallographic quality than for the AlGaN/GaN samples, which was proved by XRD-FWHM and RSM results. A substantial reduction of TD density from approximately 10 to 10 cm with increasing buffer thickness resulted in a smooth thin active region for both thick buffer structures whereas the lattice-matched InAlN/GaN-based thick buffer resulted in less effect on TD and a smooth and prominent thin active region.
ACCESSION #
109993021

 

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