Despite otherwise advantageous properties, the performance and reliability of devices manufactured in ß-Ga2O3 on semi-insulating Ga2O3 substrates may degrade because of poorly mitigated self-heating, which results from the low thermal conductivity of Ga2O3 substrates. In this work, we investigate and compare self-heating and device performance of β-Ga2O3 MESFETs on substrates of semi-insulating Ga2O3 and 4H-SiC. Electron mobility in β-Ga2O3 is negatively affected by increasing lattice temperature, which consequently also negatively influences device conductance. The superior thermal conductivity of 4H-SiC substrates resulted in reduced ß-Ga2O3 lattice temperatures and, thus, mitigates MESFET drain current degradation. This, in turn, allows practically reduced device dimensions without deteriorating the performance and improved device reliability.
