Deep-Depletion Mode Boron-Doped Monocrystalline Diamond Metal Oxide Semiconductor Field Effect Transistor

A p-type deep-depletion mode monocrystalline diamond MOSFET is demonstrated, with a 190-nm-thick controllable channel. Such a device offers new opportunities for a better optimization of the bulk doping versus designed breakdown voltage and the resulting figure of merit. Diamond MOSFETs with Boron doping of 1.75 × 10
¹⁷
cm
^-3
and using 20-nm ALD deposited Al
₂
O
₃
as the gate oxide show promising IV characteristics, with a clear ON and OFF state operation. The MOSFETs have a normally-ON operation with typical threshold voltages of V
_TH
= +7 V and a ON-state drain current of I
_SD
= 1.9 μA/mm at V
_SD
= 10 V and V
_GS
= -5 V, at room temperature. A high hole mobility (1000±200 cm
²
/(V·s)) has been evaluated.Just before the experimental voltage breakdown at 200 V, the gate leakage is still below 0.6 nA/mm at room temperature and the peak electric field in diamond at the gate edge is simulated at 4 MV/cm. Beyond this experimental proof of concept, these combined values show the high potential of deep-depletion mode Boron doped diamond MOSFETs.