((2)over-bar01) β-Gallium Oxide substrate for high quality GaN materials

((2) over bar 01) oriented beta-Ga2O3 has the potential to be used as a transparent and conductive substrate for GaN-growth. The key advantages of Ga2O3 are its small lattice mismatches (4.7%), appropriate structural, thermal and electrical properties and a competitive price compared to other substrates. Optical characterization show that GaN layers grown on ((2) over bar 01) oriented beta-Ga2O3 are dominated by intense bandedge emission with a high luminescence efficiency. Atomic force microscopy studies show a modest threading dislocation density of similar to 10(8) cm(-2), while complementary Raman spectroscopy indicates that the GaN epilayer is of high quality with slight compressive strain. Room temperature time-findings suggest that the limitation of the photoluminescence lifetime (similar to 500 ps) is due to non-radiative recombination arising from threading dislocation. Therefore, by optimizing the growth conditions, high quality material with significant optical efficiency can be obtained.