Structural and optical properties of AlxGa1−xN/GaN high electron mobility transistor structures grown on 200 mm diameter Si(111) substrates

The authors report on the study of homogeneity in structural and optical properties of AlxGa1−xN/GaN high electron mobility transistor (HEMT) structures grown on 200 mm diameter Si(111) substrates. The consequence of a variation of buffer layer thicknesses as well as the interface quality has been studied by in-situ growth monitoring. A reasonably good uniformity of crystalline quality in the heterostructures grown with a lower wafer bowing has been observed from the full width at half maxima of symmetric as well as asymmetric high resolution x-ray diffraction scans across the wafer. Furthermore, the thickness and Al content of the AlxGa1−xN barrier layer across the wafer is found to be uniform when the wafer bowing is lower. Optical and electrical measurements across the epiwafer address the strain homogeneity, luminescence, and two-dimensional electron gas properties. Based on these studies of growth optimization, HEMT epiwafers with a total nitride stack thickness of 4.4 μm with a wafer bowing <50 μm on 1.0 mm thick Si substrates are demonstrated.