16:15 - 16:45 | Tue 25 Jul | Grand Ballroom #3 | TuW4HT.2
Power electronic devices are critical components for the conversion and control of electrical power in a wide variety of applications from terrestrial-based system to space platforms. While silicon-based power devices have historically dominated the market, wide band gap materials such as gallium nitride (GaN) and silicon carbide (SiC) have gained traction in recent years, capable of withstanding higher electric fields, operating at higher ambient temperatures and capable of shorter switching times. As a result, wide band gap devices made with these materials have been smaller and faster than similar devices based on silicon, ultimately resulting in power electronic systems that perform more efficiently in their intended application. Despite this success, researchers are seeking disruptive improvements in power device performance, specifically targeting operating voltages in the 1-15 kV range. To realize these design goals, the so-called ultra-wide band gap (UWBG) semiconductors are expected to possess the required properties, most notably their larger critical electric fields for avalanche breakdown and reduced sensitivity to radiation effects. One of the newer materials to enter the discussion is beta-phase gallium oxide (β-Ga2O3), which has recently shown promising properties in preliminary device studies. With a band gap of ~4.9 eV and the expectation of being easier to dope and synthesize than aluminum nitride (AlN) and Diamond, the figure of merit for β-Ga2O3 based devices exceeds that of commercially available 4H-SiC and GaN, highlighting the potential for this material relative to current technologies. Given these potential benefits of using β-Ga2O3 for power devices, the thermal properties of the material are expected to be an area of concern. The thermal conductivity of pure β-Ga2O3 is about an order of magnitude lower than both 4H-SiC and GaN, indicating that device self-heating may be the limiting factor when it comes to the power handling capabilities of these devices. Additionally, many characteristics of real devices such as doping with impurity atoms and defects associated with both synthesis (dislocations) and degradation (radiation exposure) of the crystal will further impede phonon transport within the material, causing additional reduction to the material thermal conductivity. This presentation will focus on thermal transport in doped β-Ga2O3 single crystals and will highlight the interplay between electrical and thermal design considerations related to various performance metrics for power electronic devices.