We present a β-Ga 2 O 3 Trench Schottky Barrier Diode (SBD) featuring a high-permittivity (high-k) dielectric RESURF and an atomic layer-deposited (ALD) Ru anode contact to engineer the trade-off between forward voltage drop and reverse leakage current. We created 1 µm deep trenches on the lightly doped β-Ga 2 O 3 drift layer and deposited a high-permittivity BaTiO 3 as the RESURF dielectric. By encircling the trenches with the anode metal, the electric field at the metal/semiconductor junction is effectively reduced. Consequently, we were able to utilize a low work-function metal like Ru without inducing a significant increase in reverse leakage current. The high-k RESURF trench SBD, spanning an area of 200×200 µm 2 , demonstrated a low turn-on voltage of 0.5 V and a reverse breakdown voltage exceeding 3 kV, with a leakage current density of 2 mA/cm 2 at 3kV. The larger area 1×1 mm 2 and 2×2 mm 2 devices exhibited breakdown voltages of 1.74kV and 1.42kV, respectively, while accommodating maximum pulsed forward currents of 6A and 20A, respectively. The devices presented here exhibit record low product of stored charge and forward voltage drop (Q C V F) for > 1 A, 1 kV device, indicating promising switching and conduction loss trade-off for multi-kilovolt class applications.

We report on the demonstration of β-Ga2O3 MOSFETs fabricated on 1-inch bulk substrates using metalorganic vapor phase epitaxy (MOVPE) with disilane (Si2H6) as the silicon precursor. Sheet charge uniformity of the as-grown films was measured via Hall and ranged from 5.9 - 6.7 x 1012 cm-2 with a uniform Hall mobility of 125-129 cm2/V.s across the sample. MOSFET devices with a source-drain width of 5.1 μm were measured across the wafer and had a minimum on-resistance (RON) of 47.87 Ω.mm with a maximum on-current (ION) of 165mA/mm. For these same devices, the on-current (ION) and pinch-off voltage (VP) uniformity across the wafer were 137±12 mA/mm and -27.3±7.3 V respectively. Devices showed low reverse leakage current until catastrophic breakdown occurred, with measured breakdown voltages (VBR) of up to 2.15 kV. This work provides valuable insights into understanding the growth, fabrication, and characterization processes for β-Ga2O3 FETs on full waferscale substrates. It also projects the promise of developing lateral β-Ga2O3 FETs with high current carrying capabilities and breakdown voltages, especially on substrates of 1 inch or larger. 

This study presents design guidelines for a high-k dielectric Superjunction Schottky barrier diode (SBD) to further enhance the already impressive unipolar power figure of merit (PFOM) of Ultra-wide bandgap (UWBG) materials. We employed analytical modeling to optimize the device parameters, accounting for the appropriate dielectric and semiconductor dimensions including the aspect ratio and the dielectric constant of the highk material. Our findings reveal that device performance is intimately linked to structural dimensions and the dielectric constant of the insulator. Specifically, we observed that the dielectric superjunction SBD exhibits behavior akin to a conventional SBD, where the effective doping density in the drift layer decreases by a factor dependent on semiconductor and dielectric width, aspect ratio and the dielectric constant of the insulator. We discuss optimal design guidelines for achieving a 10 kV β-Ga2O3 SBD with a PFOM of 50 GW/cm2, a significant improvement over the conventional unipolar PFOM of 34 GW/cm2 for β-Ga2O3. Additionally, we conducted a comparative analysis of the switching energies between the superjunction Schottky barrier diode and a conventional Schottky barrier diode.We provide design guidelines to minimize switching energies for a desired PFOM in β-Ga2O3 SBDs. This underscores the immense potential of such structures in advancing vertical power electronics to unprecedented levels of performance.

We present our findings on the utilization of a high permittivity dielectric, RESURF, in β-Ga2O3 trench Schottky barrier diodes. Our research demonstrates the achievement of ultra-low reverse leakage current in both small -scale and large-scale devices, with a breakdown voltage exceeding 1kV, thanks to the high-k RESURF technology. Furthermore, we assess the switching performance of these large-area devices and illustrate their competitive standing when compared to state-of-the-art commercial SiC devices. Additionally, we provide evidence of the superior thermal stability exhibited by high-k trench devices in comparison to SiC devices.

We report a vertical β-Ga2O3 Schottky Barrier Diode (SBD) with BaTiO3 as field plate oxide on low doped thick epitaxial layer exhibiting 2.1 kV breakdown voltage. A thick drift layer of 11 μm with a low effective doping concentration of 8×1015 cm−3 is used to achieve high breakdown voltage. Using the high-k dielectric with dielectric constant of 248, the breakdown voltage increases from 816V for the non-field-plated SBD to 2152V (>2x improvement) for the field-plated SBD without compromising the on-state performance. The diode dimensions are varied to analyze the effect of edge high-field related leakage with reverse bias and also the effect of current spreading during forward operation. Very uniform distribution of breakdown voltages of 2152V±20V are observed for the diode diameters from 50 μm to 300 μm for the field-plated SBDs. The on and off state power losses are also analyzed and compared with the non-field-plated devices and the switching losses are estimated analytically.

A novel lateral β-Ga2O3 schottky diode with high permittivity dielectric superjuction technique which circumvents the lack of p-type dopants in β-Ga2O3 for high voltage applications is demonstrated. The lateral drift region was depleted from the sides in reverse bias using dielectric polarization which helps support higher electric field in the drift layer compared to conventional schottky diode. The use of such a novel dielectric superjunction structure also allows to have higher doping in the drift layer without degrading the breakdown which results in low on resistance . A dielectric superjunction schottky barrier diode with a specific on resistance of 1.65 mΩ-cm2 and a breakdown voltage of 1487 V resulting in a power figure of merit of 1.35 GW/cm2 is demonstrated.