Impact of GaN buffer layer thickness on structural and optical properties of AlGaN/GaN based high electron mobility transistor structure grown on Si(111) substrate by plasma assisted molecular beam epitaxy technique

AlGaN/GaN based double heterosturcture high electron mobility transistor (HEMT) structures were grown on GaN buffer/Si(111) substrate by plasma assisted molecular beam epitaxy (PAMBE) technique. The thickness of GaN buffer layer was varied to find out the optimum GaN buffer layer for a crack free heterostructure, exhibiting appreciable structural and optical results. Full width at half maximum (FWHM) of GaN (0002) x-ray diffraction (XRD) peak and that of top AlGaN layer was estimated to be as low as 576 arcsec and 396 arcsec respectively. Near band edge photoluminescence (PL) peak for GaN also showed a FWHM of only 21 meV. These studies show that AlGaN/GaN heterostructures epitaxially grown on Si(111) substrate with suitable GaN buffer layer using PAMBE technique are promising for HEMT application.