Campbell, Joe2015-05-142018-01-222015-05-142018-01-222003-12http://hdl.handle.net/2152/29863textVisible-blind and solar-blind ultraviolet photodetectors based on GaN/AlGaN were designed, fabricated, and characterized for commercial and military applications. High performance back-illuminated solar-blind MSM achieved external quantum efficiency of ~48%. The dark current of 40x40μm MSM was less than the instrument measurement limitation of 20fA for a bias <100V. No photoconductive gain was observed. With an n-type doped high-Al ratio "window" Al₀.₆Ga₀.₄N layer, back-illuminated solar-blind p-i-n photodiode achieved a quantum efficiency of ~55% at zero-bias. Absorption edge study of both MSM and p-i-n photodetectors, based on device spectral responses, resulted in a performance comparison of MSMs and p-i-ns, as the solar-blind photodetection requires a sharp solar-blind rejection. Photoconductive detectors and avalanche photodetectors, with the internal gain advantage, have been discussed as well. A 30μm diameter GaN avalanche photodiode achieved a gain >23, with a dark current less than 100pA. The breakdown showed a positive temperature coefficient of 0.03 V/K that is characteristic of avalanche breakdown. SiC APDs, as candidates for visible-blind applications, have been designed, fabricated and characterized. An avalanche gain higher than 10⁵, with a dark current less than 1nA, showed the potential of SiC APD replacing PMTs for high sensitivity visible-blind UV detection. A silicon-based optical receiver has been presented in the Appendix. With the photodiode internal avalanche gain ~4, a sensitivity ~-6.9dBm at 10Gbps has been achieved.electronicengCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.Visible-blindSolar-blindUltraviolet photodetectorsGaN/AlGaNMilitary applicationsMSMThesis