Normally-off hydrogen-terminated diamond field effect transistor with a bilayer dielectric of Er2O3/Al2O3

A normally-off hydrogen-terminated diamond field effect transistor with an Er2O3/Al2O3 bilayer dielectric was fabricated. Dielectric materials Er2O3 and Al2O3 were deposited on H-diamond surface using radio frequency sputtering and atomic layer deposition, respectively. The threshold voltage of the device was −0.49 V at VDS of −20 V, which indicated a normally off characteristic, that could be attributed to the low work function of Er2O3 and the polar character of amorphous Er2O3. The maximum drain-source current for the hydrogen-terminated diamond field effect transistor with 6 μm gate length was −16.1 mA/mm and the sheet carrier density integrated was 1.08 × 1013 cm−2. The maximum effective hole mobility was 110.47 cm2/V·s and the interfacial trapped charge density was 3.16 × 1012 eV−1 cm−2. This bilayer dielectric of Er2O3/Al2O3 provides an alternative plan for the fabrication of normally-off diamond device. [Display omitted] •Er2O3 layer was used as dielectric on H-diamond FETs for the first time.•This Er2O3/Al2O3 H-diamond provides an alternative plan for the fabrication of normally-off diamond device.•μeff decreased from 110.47 to 33.40 cm2V -1 s -1 with the increase of carrier density. And the maximum sheet carrier density integrated was 1.08 × 1013 cm-2.