Toward realization of Ga<inf>2</inf>O<inf>3</inf> for power electronics applications

Abstract

As a transparent conducting oxide with a large bandgap of ∼4.9 eV and associated large estimated critical electric field (E c ) strength of 8 MV/cm, β-Ga 2 O 3 (BGO) has been touted for its tremendous potential as a power switch. Power switch metrics such as Baliga's figure of merit (BFOM) estimating dc conduction losses and Huang's material figure of merit (HMFOM) incorporating dynamic switching losses are functions of E C 3 and E C respectively [1, 2]. BFOM for BGO is expected to exceed that of GaN by 400% and HMFOM for BGO is expected to be comparable to GaN. It can also be shown that for a given power loss during switching, the switch frequency (f) varies as E C 2 suggesting the potential of BGO power conversion in the GHz regime [1, 2]. The manufacturability and cost value proposition of BGO based on large area native substrate availability as shown by Huang's chip area manufacturing FOM (HCAFOM) indicate a disruptive cost advantage over GaN (330%). Additionally, the Johnson figure of merit (JFOM) representing the power-frequency product for RF amplification for BGO is similar to that of GaN indicating potential for integration of power conversion and RF applications in the same platform. Finally, Huang's high temperature figure of merit (HTFOM) shows that BGO has the lowest metric for all semiconductors compared here due to low thermal conductivity and high field strength. However, all wide bandgap power semiconductors, including diamond, face significant thermal engineering challenges relative to Si because of the inherent high energy densities of materials with large E c values. A summary of unipolar FET figure-of-merit comparisons for power semiconductors is shown in Table 1.