Thermal Dynamics in Low Thermally Conductive Ultra Wide Bandgap Semiconductors

Despite increasing the operating voltage and current density of ultra-wide bandgap devices, excessive Joule heating significantly limits UWBG devices from reaching their theoretically predicted performance. To overcome this challenge, accurate characterization of both the UWBG device temperature distribution and thin-film layer thermal properties is necessary. This talk will provide an overview of the latest thermal characterization methods used for evaluating the temperature in Gallium Oxide and AlGaN channel-based electronics. Optical techniques such as Transient Thermoreflectance Imaging (TTI) require high-energy excitation sources and high-transmission deep-UV CCD/optics to assess the peak temperature of the channel (due to their large bandgap). Furthermore, devices with air-bridges can obstruct the use of optical techniques (including Raman thermometry) from directly assessing the channel temperature. Alternatively, previous studies on WBG semiconductors have demonstrated the feasibility of monitoring the change in resistance of the gate metal to extrapolate the peak channel temperature.