Abstract: A method of preparing GaN material includes subjecting a GaN substrate to at least two cycles of Ga deposition and desorption, then applying a layer of AlN to the GaN substrate, then growing GaN on the AlN layer by molecular beam epitaxy. This results in reduced concentrations of oxygen, carbon, and silicon impurities.

Abstract: A method for patterned deposition of an arbitrary thin film on an arbitrary substrate. A GaAs substrate having a bi-layer structure deposited thereon, the bi-layer structure consisting of a bottom layer of Ge and a top layer of SiN. A photoresist deposited on the top SiN surface of the sample is patterned to form one or more desired patterned features on the sample. The Ge—SiN bi-layer structure on the patterned sample is aniostropically etched so that an undercut is formed in the Ge layer, the SiN forming an overhang over a portion of the GaAs substrate. The remaining photoresist is removed from the sample and the film is deposited on the sample to form a feature on the substrate. The remaining Ge layer is etched away and the SiN layer and film deposited on the SiN layer are lifted from the sample, leaving only the patterned features on the substrate.

Abstract: This invention pertains to an electronic device and to a method for making it. The device is a heterojunction transistor, particularly a high electron mobility transistor, characterized by presence of a 2 DEG channel. Transistors of this invention contain an AlGaN barrier and a GaN buffer, with the channel disposed, when present, at the interface of the barrier and the buffer. Surface treated with ammonia plasma resembles untreated surface. The method pertains to treatment of the device with ammonia plasma prior to passivation to extend reliability of the device beyond a period of time on the order of 300 hours of operation, the device typically being a 2 DEG AlGaN/GaN high electron mobility transistor with essentially no gate lag and with essentially no rf power output degradation.