Microwave power performance analysis of hydrogen terminated diamond MOSFET

The hydrogen terminated diamond (H-diamond) field effect transistors (FETs) have been the mainstream structure of diamond microwave power devices, but to improve their performance is still very challenging. A detailed analysis of the microwave power performance at 1GHz of a 0.5-mu m H-diamond FET with 25-nm-thick Al2O3 gate insulator is carried out by numerical simulation of the large signal transients, and a GaN high electron mobility transistors (HEMT) in similar structure is used as a reference. Compared with the output power (Pout) of 10.76 W/mm demonstrated at a quiescent drain bias (VdQ = 48 V) by the GaN HEMT, the H-diamond FET achieved about one third of Pout (3.69 W/mm) at VdQ = -57 V based on the transconductance with much lower peak intensity (less than one fifth) but better linearity. According to the location of the dynamic load line on the direct current output characteristics, the available drain current swing has been fully utilized in the Hdiamond FET. Further Pout improvement need higher bias point and larger dynamic swing of the drain voltage.