InGaN/GaN multi-quantum-well ultraviolet photosensors by capping an unactivated Mg-doped GaN layer

InGaN/GaN multi-quantum-well (MQW) metal-semiconductor-metal (MSM) photosensors with an unactivated Mg-doped GaN cap layer were fabricated and characterized. The experimental results showed that dark pits of threading dislocation termination was hardly observed after capping a thin Mg-doped GaN layer. It was also found that we could significantly suppress the dark leakage current by inserting an additional Mg-doped GaN layer due to a thicker and higher potential barrier and effective surface passivation. For InGaN/GaN MQW MSM photosensors with the unactivated Mg-doped GaN cap layer, the responsivity at 380 nm and UV to visible rejection ratio were found to be 0.366 A/W and 1.99x10(3) under 4 V applied bias. (C) 2007 American Institute of Physics.