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An Al0.75Ga0.25N/Al0.6Ga0.4N heterostructure field effect transistor with graded MBE-regrown contacts is designed, grown, and fabricated on AlN/sapphire substrate. Maximum drain current density (ID,max) of 460 mA mm?1was obtained on transistors with gate length of 130 nm. The small signal measurement shows current/power gain cutoff frequency (fT/fmax) of 40 GHz/58 GHz, respectively. Parasitic resistance is found to be a significant factor limiting the frequency performance of the devices. The high frequency performance of devices with high Al concentration AlGaN channel demonstrate potential for high power and high frequency applications.

We demonstrate zero-bias spectral responsivity in MBE-grown b-Ga2O3 planar UV-C detector with good linearity up to optical power density of 4.6 mW cm[?]2. Devices with asymmetrical metal contacts were realized on 150 nm thick b-Ga2O3 films on sapphire. The device exhibited a spectral responsivity of 1.4 mA W[?]1 at 255 nm under zero-bias condition, dark current <10 nA at 15 V and UV-to-visible rejection ratio [?]105 at 5 V. The demonstrated UV-C detector exhibited an estimated high detectivity of 2.0 x 1012 Jones at 1 V and were found to be very stable and repeatable, suggesting its potential use for focal plane arrays.

We report (010)-oriented ?-Ga2O3bevel-field-plated mesa Schottky barrier diodes grown by low-pressure chemical vapor deposition (LPCVD) using a solid Ga precursor and O2and SiCl4sources. Schottky diodes with good ideality and low reverse leakage were realized on the epitaxial material. Edge termination using beveled field plates yielded a breakdown voltage of ?190 V, and maximum vertical electric fields of 4.2 MV/cm in the center and 5.9 MV/cm at the edge were estimated, with extrinsic RONof 3.9 m?·cm2and extracted intrinsic RONof 0.023 m?·cm2. The reported results demonstrate the high quality of homoepitaxial LPCVD-grown ?-Ga2O3thin films for vertical power electronics applications, and show that this growth method is promising for future ?-Ga2O3technology.

We report silicon delta doping in gallium oxide (?-Ga2O3) grown by plasma-assisted molecular beam epitaxy using a shutter pulsing technique. We describe the growth procedures that can be used to realize high Si incorporation in an oxidizing oxygen plasma environment. Delta doping was adopted to realize thin (12 nm) low-resistance layers with a sheet resistance of 320 ?/square (mobility of 83 cm2V?1s?1, integrated sheet charge of 2.4 × 1014cm?2). A single delta-doped sheet of carriers was employed as a channel to realize a field-effect transistor with current ID,max= 236 mA/mm and transconductance gm= 26 mS/mm.