Non-polar group-III nitride semiconductor surfaces

The intrinsic structural and electronic properties of a surface are important for any further study or application of the material, especially when a high surface-to-volume ratio is obtained or the surface gets functionalized, as e.g. during growth. Due to increasing material quality over recent years, the first experimental results are now available for the non-polar group-III nitride semiconductor surface, which can be compared with previously reported theoretical calculations. While the reports on AlN and InN surfaces are still small in number, for GaN quite a lot of experimental results on the non-polar surfaces were published on the intrinsic geometric and electronic properties, the defects, the decomposition, and the effect of impurities. Furthermore, the growth on non-polar group-III nitride surfaces is a new concept to reduce undesirable piezoelectric polarization in heterostructures and the side walls of wurtzite-structured nano-wires are formed mostly by non-polar facets. Hence, we review the existing intrinsic structural and electronic properties of non-polar surfaces of group-III nitride semiconductors in this contribution. The three different non-polar surfaces of IIIV semiconductors with filled (bright green) and empty (bright red) dangling bonds: left (red) the (10\bar 10) surface of the wurtzite crystal structure, middle (blue) the (11\bar 20) surface of the wurtzite crystal structure, and right (green) the ({110}) surface of the zincblende structure. ((c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)