RF power performance evaluation of surface channel diamond MESFETs

Large-signal radiofrequency performances of surface channel diamond MESFET fabricated on hydrogenated polycrystalline diamond are investigated. The adopted device structure is a typical coplanar two-finger gate layout, characterized in DC by an accumulationlike behavior with threshold voltage V ~ 0-0.5 V and maximum DC drain current of 120 mA/mm. The best radiofrequency performances (in terms of f andf) were obtained close to the threshold voltage. Realized devices are analyzed in standard class A operation, at an operating frequency of 2 GHz. The MESFET devices show a linear power gain of 8 dB and approximately 0.2 W/mm RF output power with 22% power added efficiency. An output power density of about 0.8 W/mm can be then extrapolated at 1 GHz, showing the potential of surface channel MESFET technology on polycrystalline diamond for microwave power devices. © 2010 Materials Research Society.