High-resolution x-ray analysis of InGaN/GaN superlattices grown on sapphire substrates with GaN layers

InGaN/GaN superlattice structures grown on (0001) sapphire substrates with GaN layers were investigated by two-dimensional reciprocal space mapping of high-resolution x-ray diffraction. The results show that InGaN/GaN multi-quantum wells with fairly good crystallinity can be grown coherently on partially relaxed GaN layer irrespective of the large lattice mismatch and thermal incompatibility with the underlying substrate. Narrow and bright band edge related emissions were observed by photoluminescence measurements, indicating high quality of these InGaN/GaN superlattice structures, Our results suggest a larger band-gap bowing coefficient than the value reported in the literature. (C) 1996 American Institute of Physics.