Digital Alloys of AlN/AlGaN for Deep UV Light Emitting Diodes

We report a systematic study of the optical and electrical properties of deep ultraviolet light emitting diodes based on digital alloy structures of AlN/Al0:08Ga0:92N grown by gas source molecular beam epitaxy with ammonia. Digital alloys are formed by short period superlattices consisting of Al0:08Ga0:92N wells, 0.50 or 0.75 nm thick, and AlN barriers, 0.75 to 1.5 nm thick. For digital alloys with effective bandgap of 5.1 eV, average AlN composition 72%, we obtain room temperature electron concentrations up to 1 1019 cm 3 and resistivity of 0.005 cm and hole concentrations of 1 1018 cm 3 with resistivity of 6 cm. Light emitting diodes based on digital alloys are demonstrated operating in the range of 250 to 290 nm