Microwave operation of sub-micrometer gate surface channel MESFETs in polycystalline diamond

Metal-Semiconductor field effect transistor (MESFETs) were fabricated on hydrogen-terminated polycrystalline diamond. Fabricated MESFETs typically showed high drain-source current (140 mA/mm) and large transconductance values (60 mS/mm), with a cut off frequency f_T=10 GHz and a maximum oscillation frequency, f_MAX, up to 35 GHz. These values suggest device microwave operation in the K- band and are obtained through the fabrication of devices with geometry and active region dimensions compatible with available microelectronic technologies. Devices were realized in order to be employed in Microwave Integrated Circuits for satellite communications and high frequency power amplification, areas where diamond promises the replacement of vacuum electronics: with this perspective, our group realized a first important step formulating an equivalent circuit (EQC) model.