Low On-Resistance H-Diamond MOSFETs with 300 °c ALD-Al2O3 Gate Dielectric

Abstract

C-H diamond metal-oxide-semiconductor field effect transistors with different structures were fabricated on the same polycrystalline diamond plate. Devices A and B with 25-nm-thick high temperature (300°C) atomic layer deposition grown Al2O3 dielectric have the same source-to-drain distance of $6~\mu \text{m}$ and different gate length of ~\mu \text{m}$ and $6~\mu \text{m}$ , respectively. Both devices show ultra-high on/off ratio of over 1010 and ultra-low gate leakage of below 10-10 A and continuous measurement stability. Device B with the source/drain-channel interspaces eliminated has achieved an on resistance of $46.20~\Omega \cdot $ mm, which is record low in the reported 6- $\mu \text{m}$ H-diamond MOSFETs with the gate dielectric prepared at high temperature (≥ 300°C). Meanwhile, device B shows larger drain current in a large portion of the linear region at VGS = -6 V, and a just slightly smaller IDmax compared with device A though its LG is three times of that of device A. A simple model of ID was used to explain the physics behind this phenomenon. In addition, the breakdown voltage is 145 V for device A and 27 V for device B, corresponding to the average breakdown field of about 0.72 MV/cm and 10.8 MV/cm, respectively.