The role of GaN/AlN double buffer layer in the crystal growth and photoluminescence of GaN nanowires

Vapor-liquid-solid (VLS) growth of GaN nanowires was performed and GaN/AlN double buffer layer was employed to minimize the lattice mismatch between GaN nanowires and Si substrates. GaN nanowires grown on GaN/AlN/Si substrates showed the formation of straight nanowires with ∼50-100 nm diameter, while those grown on bare Si wafers showed formation of tangled nanowires with non-uniform diameters. High-resolution transmission electron microscopy (HRTEM) analyses on the GaN nanowires grown on GaN/AlN/Si showed high crystallinity with [1 0 -1] crystal growth direction. Furthermore, GaN nanowires grown on GaN/AlN/Si showed high intensity blue emission and almost negligible yellow luminescence.