III-Nitride UV Detector Arrays Fabricated by Combining HVPE Lateral Epitaxial Overgrowth and MBE Methods.

摘要

The work focused on the fabrication of GaN and AlGaN detectors. Material studies of AlGaN alloys have been undertaken to improve the absorption characteristics and to develop films free of cracks. The devices were fabricated in the form of Schottky barriers, p-n and p-i-n junctions. To reduce the dark current in these devices, a number of approaches were investigated (use of thick GaN templates grown by the HVPE and the LEO methods, or utilized a number AlN interlayers prior to the growth of the device structure). A lithographic mask set was developed for the deposition of detector arrays with various configurations. High quantum efficiency (70%) Schottky barriers with five orders of magnitude visible light rejection were fabricated. P-n and p-i-n detectors with dark current at low reverse bias of about 10(exp -11) Amps/sq cm were fabricated. Rapid thermal annealing in forming gas was found to reduce the junction leakage current by orders of magnitude. These devices were found to have gains higher than one, a result attributed to photoconductive gain in the dislocation regions.