Electro-thermal crosstalk revealed by Raman thermography in multi-fin β-Ga2O3 FinFETs

β - G a 2 O 3 FinFETs are promising for high-power electronic applications owing to their ultra-wide bandgap and high breakdown field. To overcome the inherently limited current capability of single-fin devices, multi-fin architectures were introduced to enhance the total on-state current. However, transfer characteristics reveal that when the fin number is increased by a factor of 16, the saturation current at VD = 10 V rises only from 0.112 to 1.22 mA—significantly below the expected linear scaling—and premature current degradation emerges at high VG. Such deviation indicates pronounced self-heating and electro-thermal coupling within densely packed fin arrays. Furthermore, under high-power operation, evident nonlinearities appear in both temperature rise and current response, further supporting the thermally driven origin of performance degradation. Raman thermography under identical per-fin current conditions reveals a much higher peak temperature (70.77 °C) in the multi-fin device compared to the single-fin counterpart (28.8 °C), confirming severe thermal crosstalk. These findings elucidate the thermal origin of the non-ideal current scalability and provide essential insights for thermally aware three-dimensional design of β-Ga2O3 FinFETs.