Employment of III-nitride/silicon heterostructures for dual-band UV/IR photodiodes.

摘要

One of the major advantages of a single pixel selective Ultraviolet and Infrared (UV/IR) photodetector is the easy integration into multi-pixel focal plane arrays (FPA) for imaging applications that play an important role in object recognition. This feature allows for added accuracy in object classification, and hence may be directly incorporated in the military for target recognition or in domestic environments for fire/flame classification.;A new concept of structures fabricated using stacked semiconducting layers to obtain a multiband spectral response is reported. Based on this approach, fabrication of visible-blind and solar-blind dual-band UV/IR photodetectors are presented. A brief overview of the properties and Molecular Beam Epitaxy (MBE) method of growth of GaN and AlxGa1-xN on silicon are presented. Optimization of the device was carried out by modeling of the electric field distribution and developing tunneling barriers. Finally the theoretical results were confirmed by actual fabrication and realization of a two pixel visible blind UV/IR and a four pixel solar blind UV/IR photodiode structure.;The optimized solar blind UV/IR photodiode UV spectral response peaks at 230 nm with a responsivity of approximately 0.0018 A/W and turns-on approximately around 265 nm (solar-blind). The IR diode response peaks at 1000 nm with a responsivity of approximately 0.01 A/W. While the optimized visible blind UV/IR detector has a peak response of 0.38 A/W at 350 nm with a sharp turn-on at 365 nm and the IR response shows a peak response at 0.055 A/W at 1000 nm.