Over 1 A Operation of Vertical-Type Diamond MOSFETs

Diamond is a promising material for p-channel power field-effect transistors (FETs) due to its remarkable physical properties. However, no diamond FETs with current characteristics exceeding 1 A have so far been reported. P-channel FETs capable of high-current operation are essential in order to realize complementary inverters with n-channel wide bandgap devices such as SiC or GaN. In this work, we designed and fabricated vertical-type diamond metal-oxide-semiconductor FETs (MOSFETs) with a trench structure, and a gate width (W G ) of 0.1 to 10 mm. For devices with W G = 10 mm and a source-drain voltage ( V DS ) of –20 V, the drain current reached 0.7 A. We obtained a maximum drain current of over 1.5 A with V DS = –20 V by connecting two devices in parallel within a chip. The drain current density and specific on-resistance at a V DS of –10 V were 85 mA/mm and 118 Ω·mm, respectively (W G = 2 mm). The leakage current in the off state is at the lower limit of the measurement (~10 -11 A) and the on/off ratio is over nine orders of magnitude.