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 ( ${W} _{\text {G}}\text {)}$ of 0.1 to 10 mm. For devices with ${W} _{\text {G}} =10$ mm and a source-drain voltage ( ${V} _{\text {DS}}\text {)}$ of –20 V, the drain current reached 0.7 A. We obtained a maximum drain current of over 1.5 A with ${V} _{\text {DS}} =$ –20 V by connecting two devices in parallel within a chip. The drain current density and specific on-resistance at a ${V} _{\text {DS}}$ of –10 V were 85 mA/mm and $118~\Omega \cdot $ mm, respectively ( ${W} _{\text {G}} =2$ mm). The leakage current in the off state is at the lower limit of the measurement ( $\sim 10^{-{11}}$ A) and the on/off ratio is over nine orders of magnitude.