Micro-array-enhanced structure–function analysis of effective thermal boundary resistance in GaN/SiN x /diamond heterostructures

The effective thermal boundary resistance (TBReff) of GaN/SiNx/diamond heterostructures is characterized using a micro-array-enhanced structure–function–transient dual interface method (SF–TDIM). To overcome the masking of the interfacial thermal resistance by the thick substrate in standard electrical measurements, surface-patterned etched micro-arrays are employed to reduce the effective heat-flow area and geometrically amplify the interfacial resistance contribution, while a high-precision temperature-sensing chip captures the thermal transient with negligible switching delay. For a structure with a 25-nm SiNx interlayer, SF–TDIM yields TBReff=35.2±6.4 m2K/GW (k=2), with consistent area-normalized results obtained from three array geometries. The result agrees, within the respective uncertainty intervals, with an independent transient thermoreflectance measurement on an unetched reference from the same fabrication batch. This work provides a practical electrical route with enhanced sensitivity for evaluating thermal transport across heterostructure interlayers.