β-Ga₂O₃ Lateral High-Permittivity Dielectric Superjunction Schottky Barrier Diode With 1.34 GW/cm² Power Figure of Merit

Abstract

In this work, we demonstrate lateral β-Ga 2 O 3 Schottky barrier diode (SBD) with a high permittivity (highk) dielectric superjunction (SJ) structure. Trenches are patterned on the doped β-Ga 2 O 3 epilayer from anode to cathode and high permittivity BaTiO 3 dielectric is deposited on the trenches to uniformly distribute the electric field in the epilayer, which circumvents the extreme difficulties in achieving charge balance using conventional p-n superjunction structures in β-Ga 2 O 3 due to the lack of shallow acceptors. The proposed structure also enables the use of heavily doped epilayer to reduce on-resistance and also can achieve high breakdown voltage due to charge balance effect arising out of dielectric polarization. SBD on an epilayer with a sheet charge of 1.5×10 13 cm −2 demonstrates a specific on resistance (R on−sp ) of 1.65 mΩ-cm 2 and a breakdown voltage (V BR ) of 1487 V for an anode to cathode length of 5 µm rendering a Power figure of Merit (PFOM) of 1.34 GW/cm 2 when normalized to the entire device footprint. Normalizing to the active current conducting area yields a PFOM of 2.7 GW/cm 2 which crosses the SiC unipolar PFOM. These results using the proposed device structure demonstrates great promise for β-Ga 2 O 3 in multi-kilovolt class applications.

Vertical metal–dielectric–semiconductor diode on (001) β-Ga2O3 with high-κ TiO2 interlayer exhibiting reduced turn-on voltage and leakage current and improved breakdown

“…5(a). 7,[9][10][11][12][15][16][17][18][19][20][21]29,31,32,34) The / V R bk 2 on,sp of 480 MW cm −2 is the highest reported for MDS diode on β-Ga 2 O 3 and is in-class with several other recent β-Ga 2 O 3 diode reports. However, this is accomplished with a very low V .…”

“…This field management benefit is expected with the high κ due to the induced polarization charge at the dielectric-semiconductor interface. 29,30) However, the MDS F br is substantially lower than the theoretical 8 MV cm −1 for β-Ga 2 O 3 , indicating the presence of strong field crowding at the anode edges. In addition, the TiO 2 interlayer results in a reduction of reverse bias current by several orders of magnitude for the MDS diode versus the SBD.…”

“…5. (a) BFOM plot benchmarking the present R on,sp and V bk results against state-of-the-art β-Ga 2 O 3 diodes in literature, (b) BFOM plot with effective R on,sp from V F at 100 A cm −2 forward current density, 7,9-12,[15][16][17][18][19][20][21]29,31,32,34) and (c) calculated P loss versus duty cycle and ideal Buck converter voltage ratio for the devices in this work with V F at 100 A cm −2 and J R at −500 V used to calculate losses.…”

2.1 kV (001)-β-Ga2O3 Vertical Schottky Barrier Diode with High-k Oxide Field Plate

“…The availability of highquality melt grown bulk substrates also results in superior epitaxial layer growth 2 and potentially reduced cost. The rapid advances in materials development also enabled many state of the art device realization in both vertical and lateral geometry [3][4][5][6][7][8][9][10][11][12][13][14][15][16] . Vertical devices are of particular interest for high voltage applications due to their superior scalability to high currents compared to lateral devices.…”

“…Standard solvent clean (Acetone/Methanol/DI water) was performed before device fabrication. After solvent cleaning 300 nm thick BaTiO 3 was deposited using RF sputtering at room temperature in oxygen ambient with O 2 /Ar ratio of 1:10 and at a sputter power of 140W and chamber pressure of 5mTorr 12,23 . Af- ter the dielectric deposition, the samples were annealed at 700 0 C in oxygen ambient for 30 minutes to enhance the dielectric constant.…”