Thermal characterization of MBE-grown GaN/AlGaN/GaN device on single crystalline diamond

Self-heating effects in a molecular beam epitaxy-grown GaN/AlGaN/GaN structure on a single crystalline diamond is investigated. A transient interferometric method, in combination with a three dimensional model, is used to describe a pulsed operation of a transistor-like heater, and a micro-Raman technique is used in a steady state. Good agreement is found between the techniques. The thermal conductivity of the diamond is found to be 2200 W/m K, and the thermal boundary resistance to the III-N epi-structure is < 1 × 10−8 m2 K/W. The excellent cooling efficiency of the diamond is manifested by the fast saturation of the temperature at 1 μs and by a record low normalized thermal resistance of 3.5 K mm/W.