Contactless Thermal Boundary Resistance Measurement of GaN-on-Diamond Wafers

Low thermal resistance GaN-on-diamond wafers offer enhanced thermal management with respect to GaN-on-SiC devices. The GaN/diamond interfacial thermal resistance can contribute significantly to the total device thermal resistance and must therefore be minimized to gain the maximum benefit from GaN-on-diamond. A contactless thermoreflectance measurement technique has been developed, which can be used after wafer growth and before device fabrication, enabling rapid feedback about the influence of growth parameters on interfacial thermal resistance. A measured 2x reduction in the GaN/diamond interfacial resistance is achieved by reducing the dielectric thickness between the GaN and diamond from 90 to 50 nm, enabling a potential 25% increase in transistor power dissipation for GaN-on-diamond.