Fabrication of ultra-violet photodetector on laser MBE grown epitaxial GaN nanowalls on sapphire (11–20)

We have grown epitaxial GaN nanowalls network (NWN) on AlN buffered pre-nitridated sapphire (11–20) substrate using AlN buffer by laser-assisted molecular beam epitaxy (LMBE) technique at 700 °C. The scanning electron microscopy measurement revealed the formation of honeycomb GaN NWN having a wall width ~ 15–30 nm and pore sizes of 150–250 nm. High-resolution X-ray diffraction analysis disclosed the highlyc-axis-oriented growth of hexagonal GaN structure. X-ray photoemission spectroscopy study reveals the formation of AlN buffer on pre-nitridated sapphire. A low value of tensile biaxial stress (~ 0.12 GPa) shows that GaN NWN grown on sapphire (11–20) is nearly stress free. Further, we have fabricated a metal–semiconductor–metal ultra-violet (UV) photodetector (PD) on GaN NWN and studied photo-response behaviour of UV PD device. We have obtained the photoresponsivity of 0.46 A/W at 3 V with detectivity of ~ 2.18 × 107Jones and noise equivalent power (NEP) of ~ 3.6 × 10–10W/Hz1/2for the fabricated GaN NWN PD.Graphical abstract