Boron-doped diamond MOSFETs operating at temperatures up to 400°C

The boron-doped diamond (B-diamond) metal-oxide–semiconductor field–effect transistors (MOSFETs) are fabricated and characterized at operating temperatures up to 400°C. The SiO₂ serves as the gate oxide insulator, while the Ti/Pt bilayer is employed as the gate contact metal. As the operating temperature rises from room temperature (RT) to 400°C, the absolute drain current maximum for the B-diamond MOSFET increases from 3.9 μA mm⁻¹ to 177.4 μA mm⁻¹. Conversely, the on-resistance decreases significantly from 1469.8 kΩ mm to 16.5 kΩ mm. The on/off ratio for the MOSFET at RT is 1.9 × 10⁵, which increases to over 5.0 × 10⁶ at temperatures exceeding 100°C. The threshold voltage exhibits a decreasing trend, though it deviates from this trend at 300°C. The subthreshold voltage and extrinsic transconductance maximum show increasing trends from 113 mV dec⁻¹ to 299 mV dec⁻¹ and from 0.9 μS mm⁻¹ to 23.1 μS mm⁻¹, respectively. The interfacial trapped charge density is found to be stable in the range of 8.0 × 10¹¹–2.3 × 10¹² eV⁻¹cm⁻².