Effect of thermal annealing on GaN pn-junction diode with Pt/Ag as ohmic contact

In this paper, the effect of thermal annealing on gallium nitride (GaN) pn-junction photodiode grown on Si(1 1 1) by RF-plasma assisted molecular beam epitaxy is described. Platinum (Pt) and silver (Ag) were used as ohmic contact for GaN pn-junction photodetector. The structural evolution and temperature dependence of the current of Pt/Ag contacts on GaN pn-junction at various annealing were investigated by scanning electron microscopy, atomic force microscopy, high resolution X-ray diffraction, and current–voltage (I–V) measurements, respectively. The temperature dependence of the current may be attributed to changes of the surface morphology and surface roughness of Pt/Ag contacts on the sample. The lower surface roughness was achieved at thermal annealing temperature of 700 °C.