7.5 kV, 6.2 GW cm−2 NiO/β-Ga2O3 vertical rectifiers with on–off ratio greater than 1013

Abstract

Vertical geometry NiO/β n-Ga2O/n+ Ga2O3 heterojunction rectifiers with contact sizes from 50 to 200 μm diameter showed breakdown voltages (VB) up to 7.5 kV for drift region carrier concentration of 8 × 1015 cm−3. This exceeds the unipolar 1D limit for SiC and was achieved without substrate thinning or annealing of the epi layer structure. The power figure-of-merit, VB2/RON, was 6.2 GW cm−2, where RON is the on-state resistance (9.3–14.7 mΩ cm2). The average electric field strength was 7.56 MV/cm, approaching the maximum for β-Ga2O3. The on–off ratio switching from 5 to 0 V was 2 × 1013, while it was 3 × 1010–2 × 1011 switching to 100 V. The turn-on voltage was in the range 1.9–2.1 V for the different contact diameters, while the reverse current density was in the range 2 × 10−8–2 × 10−9 A cm−2 at −100 V. The reverse recovery time was 21 ns, while the forward current density was >100 A/cm2 at 5 V.

The Optimization of NiO Doping, Thickness, and Extension in kV-Class NiO/Ga2O3 Vertical Rectifiers

“…The ultra-wide-bandgap semiconductor, Ga 2 O 3 , has advantages over Si electronics in terms of the ability to achieve higher breakdown voltage and lower on-state resistance [1][2][3][4][5][6][7][8][9]. Recent demonstrations of the ability of NiO/β-Ga 2 O 3 vertical geometry rectifiers to achieve excellent performance [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] and breakdown voltages in excess of 8 kV [7,[25][26][27] has revitalized interest in the heterojunction approach to overcome the lack of a practical p-type doping capability for β-Ga 2 O 3 . Several groups have now demonstrated devices with breakdown voltage and on-state resistance beyond the 1D limit of both GaN and SiC, showing the increasing maturity of Ga 2 O 3 power device technology [7,25].…”

“…The thickness, doping concentration, and extension beyond the anode are varied within the simulation and compared to experimental data. We calibrated the basis of the simulations with real experimental data [15,[25][26][27], as shown below, but the main part of the manuscript is on the simulations themselves, which are designed to allow for the design and optimization of the next generation of rectifiers with an even higher performance.…”

1 mm2, 3.6 kV, 4.8 A NiO/Ga2O3 Heterojunction Rectifiers

“…47,48 Such devices exhibit breakdown fields >8.5 MV.cm −1 , establishing this as a lower limit for β-Ga 2 O 3 . 49…”

Superior high temperature performance of 8 kV NiO/Ga2O3vertical heterojunction rectifiers

“…The forward current transport mechanism in such junctions is typically recombination at low biases and trap-assisted tunneling at higher bias. 10,21–26 Promising rectifier performance has been reported with this approach, 14–36 including V B of 8.32 kV, with figure of merit 13.2 GW cm −2 . 15…”