pn-Junction photodiode based on GaN grown on Si (111) by plasma-assisted molecular beam epitaxy

The growth and characterization of pn-junction photodiode based on GaN grown on Si (111) by RF-plasma assisted molecular beam epitaxy (MBE) are described. The structural and optical properties of samples were studied by HR-XRD and Fourier FTIR spectroscopy, respectively. For IR reflectance analysis, GaN-like and AlN-like E2 TO optical modes have been detected. By using the thermal evaporator, Ni/Ag and Al contacts were evaporated at the front and back of samples. The application of thermal annealing treatment in oxygen ambient has been shown to significantly reduce the dark current of GaN pn-junction photodiode. The electrical characteristics of all samples were conducted using Keithley's I-V measurement system. Under 460-nm wavelength, at bias voltages of 0.5, 1, and 2 V, the photocurrents rise and decay times were investigated.