| High-performance GaN- and AlxGa1- xN-based ultraviolet photodetectors were designed, fabricated, characterized, and modeled for use in emerging commercial and military visible-blind and solar-blind sensing and imaging. Homojunction GaN p-i-n photodetectors and heterojunction AlxGa 1-xN/GaN p-i-n photodetectors achieved record low dark current densities, and record high external quantum efficiencies of ∼77% with a recessed-window structure that was developed based on an analysis of the spectral external quantum efficiency. Design and simulation of a GaN resonant-cavity-enhanced wavelength-selective UV photodetector with a nitride-based Bragg reflector, and design and fabrication of a notch-filter integrated GaN p-i-n photodetector were also accomplished. A back-to-back Schottky metal-semiconductor-metal ultraviolet photodetector on an MBE-grown GaN film exhibited low dark current, high quantum efficiency, and absence of gain. A back-illuminated solar-blind heteroepitaxial Al xGa1-xN p-i-n photodiode exhibited low dark current density, high visible-to-UV rejection ratio, record low noise power density, and high detectivity. A Schottky metal-semiconductor-metal solar-blind AlxGa 1-xN photodetector also exhibited low dark current, high quantum efficiency, high visible-to-UV rejection ratio, low noise, high detectivity, and a 3-dB bandwidth of ∼100 MHz. |
