High-voltage vertical Ga2O3 power rectifiers operational at high temperatures up to 600 K

Abstract

This work presents the temperature-dependent forward conduction and reverse blocking characteristics of a high-voltage vertical Ga2O3 power rectifier from 300 K to 600 K. Vertical β-Ga2O3 Schottky barrier diodes (SBDs) were fabricated with a bevel-field-plated edge termination, where a beveled sidewall was implemented in both the mesa and the field plate oxide. The Schottky barrier height was found to increase from 1.2 eV to 1.3 eV as the temperature increases from 300 K to 600 K, indicating the existence of barrier height inhomogeneity. The net donor concentration in the drift region shows little dependence on the temperature. The reverse leakage current up to 500 V was found to be limited by both the thermionic-field electron injection at the Schottky contact and the electron hopping via the defect states in the depletion region. At 300–500 K, the leakage is first limited by the electron injection at low voltages and then by the hopping in depleted Ga2O3 at high voltages. At temperatures above 500 K, the thermionic field emission limits the device leakage over the entire voltage range up to 500 V. Compared to the state-of-the-art SiC and GaN SBDs when blocking a similar voltage, our vertical Ga2O3 SBDs are capable of operating at significantly higher temperatures and show a smaller leakage current increase with temperature. This shows the great potential of Ga2O3 SBDs for high-temperature and high-voltage power applications.

TCAD-Machine Learning Framework for Device Variation and Operating Temperature Analysis With Experimental Demonstration

“…The WF variation is mainly produced by various surface treatment mentioned in Section II. The consideration of the WF variation is essential to mimic the barrier height inhomogeneity widely reported in Ga2O3 SBDs [13][22] [23].…”

“…Since the operating temperature of each device is known from the chuck temperature calibrated by thermal camera and device WF can be extracted by electrical methods (e.g. from the sub-threshold region of the forward I-V curve based on the thermal emission model [13] [29]), the ML predicted T and WF can be plotted against the known values of all devices. Fig.…”

“…Polycrystalline Ga 2 O 3 sensors have been demonstrated to operate at over 500 o C [8]. Single crystalline Ga2O3 power devices with hundreds of volts breakdown voltage have been demonstrated to function at 350 o C [13]. However, as a nascent material and device technology, Ga2O3 electronics suffer from considerable epitaxy and process non-uniformity and therefore require extensive variation analysis in its development.…”

“…The SOG was then opened through wet etch, followed by the metal deposition to form Schottky contacts and field plates. More details of device fabrication are described in [13] and [14]. Before the Schottky metal deposition, the wafer was cut into small samples, and different surface chemical treatment (water, hydrochloric acid, buffered oxide etch) were applied to intentionally introduce the variations in the Schottky barrier height [15].…”

Packaged Ga2O3 Schottky Rectifiers With Over 60-A Surge Current Capability

“…The substrate was thinned down to a thickness of 500 µm. The device fabrication is similar to those reported in [3], [16]. A Ti/Au (30/150 nm) Ohmic contact was formed as the cathode.…”