... Effect of substrate temperature on spontaneous GaN nanowire growth and optoelectronic properties A.P. Vajpeyia,b,Ã, A. Georgakilasa,b, G. Tsiakatourasa,b, K. Tsagarakia,b, M. Androulidakia,b,S.J. ... selectionrules for wurtzite GaN. The inset in Fig. 3 is an expansion of theRaman spectrum in the vicinity of the E2(high) phonon peak of GaN NWs and the GaN film. The E2(high) phonon line of ... promising semiconductor materials because of their application in optoelectronics and high-power electronicdevices. One of the major problems of III-nitride materialshetroepitaxial growth is high...