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We demonstrate field emission characteristics of β-Ga2O3 nano-pillar arrays fabricated using a damage-free etching technique. The technique utilizes Ga flux in an ultra-high vacuum environment (molecular beam epitaxy) to form high aspect ratio Ga2O3 nano-pillars with atomic-scale etching precision. Electrically conductive Ga2O3 nano-pillars with uniform widths of ∼200–300 nm were realized without the use of e-beam lithography. Furthermore, field emission characteristics on the nano-pillars displayed an emission current of 19 nA per tip at an electric field of 385 kV/cm. The field emission characteristics were modeled using the Murphy–Good model, and the measurements were validated with a field emission orthodoxy test.

Modulation-doped heterostructures are a key enabler for realizing high mobility and better scaling properties for high performance transistors. We report the realization of a modulation-doped twodimensional electron gas (2DEG) at the β-(Al0.2Ga0.8)2O3/Ga2O3 heterojunction by silicon delta doping. The formation of a 2DEG was confirmed using capacitance voltage measurements. A modulation-doped 2DEG channel was used to realize a modulation-doped field-effect transistor. The demonstration of modulation doping in the β-(Al0.2Ga0.8)2O3/Ga2O3 material system could enable heterojunction devices for high performance electronics. [ABSTRACT FROM AUTHOR]

In this report, we demonstrate high spectral responsivity (SR) in MBE grown epitaxial β-Ga2O3- based solar blind metal-semiconductor-metal (MSM) photodetectors (PD). The (-201)-oriented β-Ga2O3 thin film was grown using plasma-assisted MBE on c-plane sapphire substrates. MSM devices fabricated with Ni/Au contacts in an interdigitated geometry were found to exhibit peak SR>1.5 A/W at 236–240 nm at a bias of 4V with a UV to visible rejection ratio>105. The devices exhibited very low dark current<10 nA at 20V and showed no persistent photoconductivity (PPC) as evident from the sharp transients with a photo-to-dark current ratio>103. These results represent the state-of-art performance for the MBE-grown β-Ga2O3 MSM solar blind detector. [ABSTRACT FROM AUTHOR]

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−1 was 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. [ABSTRACT FROM AUTHOR]

We report (010)-oriented β-Ga2O3 bevel-field-plated mesa Schottky barrier diodes grown by low-pressure chemical vapor deposition (LPCVD) using a solid Ga precursor and O2 and SiCl4 sources. 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 RON of 3.9 mΩ·cm2 and extracted intrinsic RON of 0.023 mΩ·cm2. The reported results demonstrate the high quality of homoepitaxial LPCVD-grown β-Ga2O3 thin films for vertical power electronics applications, and show that this growth method is promising for future β-Ga2O3 technology. [ABSTRACT FROM AUTHOR]

We report silicon delta doping in gallium oxide (β-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 Ω/square (mobility of 83 cm2 V−1 s−1, integrated sheet charge of 2.4 × 1014 cm−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. [ABSTRACT FROM AUTHOR]