Defect mediated self-powered, broad band and ultrafast InGaN based photodetector

In this work, Si doped n+-InGaN epilayer has been grown on a 100 nm thick AlN template on an n-type Si (111) substrate to form semiconductor-insulator-semiconductor (SIS) heterostructure by plasma-assisted molecular beam epitaxy (PAMBE). The n+-InGaN/AlN/n-Si (111) device shows excellent self-powered and broad band photo response under UV-Visible (300-800 nm) light illumination and maximum response is observed at 580 nm for low intensity irradiance (0.1 mW/cm²), owing to the intermediate energy states present in InGaN lattice due to nitrogen vacancies. At zero bias, the device exhibits a high responsivity of 9.64 A/W with ultrafast rise and fall times of 19.9 and 21.4 μs, respectively. This is the highest reported responsivity for the InGaN based photodetectors at zero bias to best of our knowledge. Introduction of AlN buffer layer and doping enhance the photoelectrical properties of the device compared to other conventional detectors. This work opens up a new avenue for SIS heterojunction photo detectors with much improved performance as self-powered and broadband detectors over the previously reported values on InGaN.