Abstract
Efficient and ultrafast (aluminum)-gallium-nitride-based
metal-semiconductor-metal (Alx)Ga1–xN ultraviolet photodiodes were
implemented to investigate the spectral properties of GaN/AlGaN-based
photodetectors. Al composition of the GaN templates were varied from
0-% to 30% to demonstrate the impact of Al mole fraction on the cutoff
wavelength of these UV photodiodes. Asymmetric metal contact electrodes
were fabricated to optimize the external quantum efficiency without
compromising their ultrafast photoresponse. The best performing devices
exhibited a peak response of 4 V and an oscilloscope limited temporal
pulse width of 61 ps at a 20-V bias with a peak spectral responsivity of
36.5 mA/W at 280 nm.