Comprehensive investigation on the correlation of growth, structural and   optical properties of GaN nanowires grown on Si(111) substrates by plasma   assisted molecular beam epitaxy technique
  The present study elucidates the correlation between the structural and optical properties of GaN nanowires grown on Si(111) substrate by plasma assisted molecular beam epitaxy (PA-MBE) technique under various growth conditions. GaN NWs exhibiting different shapes, sizes and distribution were grown at various substrate temperatures with same Ga-N (III-V) ratio of 0.4. We observe that sample grown at lower substrate temperature (~700 degC) results 2-dimensional island like structure with almost very little (~30%) circularity while increasing substrate temperature (>770 degC) leads to growth of individual GaN NW (>80% circularity) with excellent structural properties. The temperature dependent photoluminescence measurement together with analysis of RAMAN active modes provides legitimate evidences of strong correlation between the structure and optical properties GaN nanowires grown on Si substrates. 
Ritam Sarkar, R. Fandan, Krista R. Khiangte, S. Chouksey, A. M.   Josheph, S. Das, S. Ganguly, D. Saha and Apurba Laha
cond-mat.mtrl-sci