Reverse Breakdown in Large Area, Field-Plated, Vertical β-Ga₂O₃Rectifiers

Abstract

There is interest in developing large area Ga 2 O 3 rectifiers for applications in hybrid power converters. Vertical geometry, Schottky rectifiers with area 1.2 × 1.2 mm 2 fabricated on thick (8μm), undoped (n = 4.4 × 10 15 cm −3) β-Ga 2 O 3 epitaxial layers oN conducting bulk substrates exhibit both high forward current (1A in pulsed mode) and reverse breakdown voltage (V B = 760V). This breakdown voltage was ∼200V higher than rectifiers without the presence of a bilayer SiO 2 / SiN x field plate. This edge termination is critical for obtaining high breakdown voltage by reducing electric field crowding around the metal contact periphery. Optimization of the field plate design is still needed, since devices are observed experimentally to breakdown at the contact periphery. When purposely driven to failure at high reverse bias, pits are observed in the high field regions at the edge of the contact. The specific on-resistance (R on) for these large area rectifiers was 22 m .cm −2 , with a figure-of-merit V B 2 /Ron of 26 MW.cm −2. The potential of Ga 2 O 3 for power electronics is clear when it is realized that these values are still an order of magnitude lower than theoretical values. The diode on-off ratio was in the range 2.7 × 10 7-2.2 × 10 9 when switching from +1.5V forward bias to 1-100V reverse bias.

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

“…The switching characteristics of the rectifiers are also of paramount interest, since they need fast recovery times and the ability to switch large currents. [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63] Fig. 9 shows the temperature dependence of (top) Schottky rectifiers and (bottom) NiO/ Ga 2 O 3 heterojunction rectifiers of reverse recovery characteristics in which the devices were switched from 60 mA forward current to 0 V. The reverse recovery times are B 26 AE 2 ns and are tabulated in Table 1.…”

A Comprehensive Review on Recent Developments in Ohmic and Schottky Contacts on Ga2O3 for Device Applications

“…Several researchers have reported using a field plate (FP) edge termination technique to redistribute the electric field at the SC metal periphery under reverse bias. − Konishi et al fabricated FP-SBDs on HVPE-grown (001) epilayers on highly doped bulk conducting β-Ga 2 O 3 substrate as shown in Figure . Based on a two-dimensional device simulation using Silvaco ATLAS, a doping density of about 1 × 10 16 cm –3 in the drift region of 300 nm thick SiO 2 dielectric and FP length of 20 μm were targeted.…”

-GaO Field Plate Schottky Barrier Diode With Superb Reverse Recovery for High-Efficiency DC–DC Converter

“…7, a current of 2 A can be obtained at the forward voltage of 2 V (50-μs pulse width and 1% duty cycle), meanwhile, the breakdown voltage is 467 V, which is relatively superior to other large-area SBDs as shown in Fig. 8 [13,[42][43][44], and can be utilized to provide sufficient safety area for the implementation of 350 V-output circuit.…”