Comparative Study of AlGaN/GaN HEMTs on Free-Standing Diamond and Silicon Substrates for Thermal Effects

In this work, we compare for the first time the performance results of AlGaN/GaN HEMTs processed on a free-standing chemical vapor deposition (CVD) polycrystalline diamond substrate and a silicon substrate with nominally the same epitaxial AlGaN/GaN layers both grown by metal-organic chemical vapor deposition (MOCVD). The objective of this work is to compare the small signal and DC trends of the transistors fabricated on the different substrates as a function of temperature. Wafer scale results were obtained from both wafers for 2 x 150 µm devices with gate lengths of 0.18µm and 0.20µm for the silicon and CVD diamond wafers respectively.