High breakdown voltage of boron-doped diamond metal semiconductor field effect transistor grown on freestanding heteroepitaxial diamond substrate

We report the results of a device performance of a boron-doped diamond metal semiconductor field effect transistor (MESFET) grown on a heteroepitaxial diamond substrate using microwave plasma chemical vapor deposition. The 120 nm-thick lightly boron-doped p-type diamond layer indicates sheet resistance of 6 G Omega/sq. at room temperature (RT). A two-terminal buffer leakage test with pad distance of 10 mu m shows that a heteroepitaxial grown diamond substrate withstands more than 3 kV. The fabricated device with gate-drain distance (L-gd) of 10 mu m exhibits a drain current density (I-d) of 66 nA/mm (gate voltage (V-sg) 0.5 V, drain voltage (V-ds) 30 V, and at RT), and at 463 K, the Id increases to 9.4 mu A/mm. The device with Lgd of 30 mu m shows a high breakdown voltage of -2360 V at RT, and at 463 K, breakdown voltage reduces to -515 V owing to an increase in leakage current. A benchmark on breakdown voltage vs. on-resistance reveals that our breakdown result at RT is the highest value ever reported for a bulk p-doped diamond FETs.