Synthesis Porous GaN by Using UV-assisted Electrochemical Etching and Its Optical Studies

The PL of porous GaN sample shows higher intensity with smaller FWHM and red-shifting relative to the as-grown sample. The energy gap for porous GaN sample was smaller compare to the as-grown sample. The SEM surface image of UV-assisted electrochemical etching process is shown a shape and size of pore which was formed on the surface of the GaN, therefore the shape of pores formed was in spherical shape. The size of the pores formed has diameter as small as 85 nm. Two PL peaks were observed in the as-grown and porous GaN sample. For the as-grown GaN, the higher peak was observed at “361.946 nm†and the other at “723.739 nm†which is in UV and red luminescence region respectively. The FWHM is “8.198 nm†at “361.946 nm†. For the porous GaN, the higher peak was observed at “364.235 nm†and at “728.039 nm†, so their FWHM are “4.244 nm†and “8.926 nm†respectively. The peaks of porous sample were red-shifted at “2.289 nm and 4.30 nm†respectively compare to the peaks of the as-grown GaN. PL intensity of the porous samples was observed to be increased. Raman peaks representative to the wurtzite GaN crystal, namely E2 (low) at 142.426 cm-1, E2 (high) at 568.771 cm-1,  and A1 (LO) at 736.769 cm-1 were clearly observed.