H-diamond MOS interface properties and FET characteristics with high-temperature ALD-grown HfO2 dielectric

The performance of hydrogen-terminated diamond MOSFETs with a large gate–drain interspace (LGD) was analyzed on a polycrystalline diamond sample. A 300 °C atomic layer deposition grown (ALD-grown) HfO2 dielectric (28 nm) was used the gate dielectric and device passivation layer. The HfO2/H-diamond interfacial valence band offset of 1.98 eV was determined by x-ray photoelectron spectroscopy, indicating that the high temperature grown HfO2 dielectric has great potential for accommodating a high density of holes on the H-diamond surface, and the high dielectric constant of HfO2 is also useful for improving the control capability of the gate on the device channel. A breakdown voltage of 657 V was achieved on the device. Baliga’s figure of merit of the device was calculated to be ∼2.0 MW/cm2, which is comparable to that of the H-diamond FETs with Al2O3 dielectrics that are more than 200 nm thick. The HfO2 dielectric shows great potential for use in H-diamond power devices.