Structure for a gallium-nitride (GaN) based ultra-violet light detector

A structure for a gallium-nitride (GaN) based ultra-violet light detector is provided. The structure contains a n-type contact layer, a light absorption layer, a light penetration layer, and a p-type contact layer, sequentially stacked on a substrate from bottom to top in this order. The layers are all made of aluminum-gallium-indium-nitride (AlGaInN) compound semiconductors. By varying the composition of aluminum, gallium, and indium, the layers, on one hand, can achieve the desired band gaps so that the light detector is highly responsive to an ultra-violet light of a specific wavelength. On the other hand, the layers have compatible lattice constants so that problems associated with excessive stress are avoided and high-quality epitaxial structure is obtained. The structure further contains a positive electrode, a light penetration contact layer, and a anti-reflective coating layer on the p-type contact layer, and a negative electrode on the n-type contact layer.