Watschke, LarsLarsWatschkePassow, ThorstenThorstenPassowFuchs, FrankFrankFuchsKirste, LutzLutzKirsteDriad, RachidRachidDriadRutz, FrankFrankRutzLeone, StefanoStefanoLeoneRehm, RobertRobertRehmAmbacher, OliverOliverAmbacher2022-03-062022-03-062019https://publica.fraunhofer.de/handle/publica/25867710.7567/1347-4065/ab138fAlxGa1−xN-based avalanche photodiodes with a Schottky-contact grown on AlN bulk substrate with an Al-content of x = 0.68 have been examined with respect to their structural and electro-optical properties. The Schottky diodes suitable for the solar-blind ultraviolet spectral regime show avalanche gain for voltages in excess of 25 V reverse bias in linear gain mode under frontside illumination. For 60 V reverse bias, avalanche multiplication exceeding 104 was obtained. The devices were operated well below breakdown; the measured current for frontside illuminated conditions exceeds the dark-condition characteristics by more than two orders of magnitude at this voltage. The Schottky-barrier height FB and the ideality n were extracted to FB = 2.06 eV and n = 1.26 at room temperature, respectively. Temperature dependent measurements indicate a temperature insensitive dark current mechanism with an enhanced multiplication process towards lower temperatures.en621530journal article