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 AIN buffered pre-nitridated sapphire (11-20) substrate using AIN buffer by laser-assisted molecular beam epitaxy (LMBE) technique at 700 degrees C. The scanning electron microscopy measurement revealed the formation of honeycomb GaN NWN having a wall width similar to 15-30 nm and pore sizes of 150-250 nm. High-resolution X-ray diffraction analysis disclosed the highly c-axis-oriented growth of hexagonal GaN structure. X-ray photoemission spectroscopy study reveals the formation of AIN buffer on pre-nitridated sapphire. A low value of tensile biaxial stress (similar to 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 similar to 2.18 x 10(7) Jones and noise equivalent power (NEP) of similar to 3.6 x 10(-)(1)0 W/Hz(1/2 )for the fabricated GaN NWN PD.