Over 1kV Deep Depletion Diamond MOSFET

Two deep depletion diamond metal-oxide-semiconductor field-effect transistors (D3MOSFETs) are introduced. The first is a fingered transistor designed to parallelize several similar devices and create interdigitated structures. The device has a gate width of 630 $\mu\mathrm{m}$ and delivers a 2.5 mA current at $\mathrm{V}_{\text{DS}}=-15\mathrm{V}, \mathrm{V}_{\text{GS}}=-10\mathrm{V}, 450\mathrm{K}$ I with a grounded backside. Its specific ON-resistance and threshold voltage are 400 $\mathrm{m}\Omega\cdot \text{cm}^{2}$ and 19 V, respectively. The breakdown voltage was measured at 362 V at 300 K. Several functional devices were demonstrated, enabling the possibility of achieving a total current exceeding 50 mA by paralleling multiple working fingers. The second device is an elementary D3MOSFET. Its gate width was 130 $\mu\mathrm{m}$, and its current was 38 $\mu \mathrm{A}$ ‘ By biasing the backside from 0 V to -30 V, the current increased from 38 $\mu \mathrm{A}$ to 200 $\mu \mathrm{A}$ I corresponding to a $\mathrm{R}_{\text{ON}}.\mathrm{S}$ of 1.2 $\Omega\cdot \text{cm}^{2}(450\mathrm{K})$. The threshold voltage was measured at 2 V, and the breakdown voltage exceeded 1 kV at 300 K. This breakdown voltage value is the highest reported for a D3MOSFET, corresponding to simulated peak electric fields of 3.1 MV/cm, 6.5 MV/cm and 7.1 MV/cm respectively in the diamond drift region, Ah03 gate oxide and SbN4 passivation.