International Conference on Solid State Devices and Materials

We report the improvement of the contact resistance and the subthreshold swing (SS) in (001) hydrogen-terminated (C-H) diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) by introducing a heavily boron doped (p⁺) layer as source and drain (S/D) regions. The p⁺ layer ([B]: 2~8 × 10²⁰ cm^-3 ) reduced the contact resistance (R_c) to 1.4 Ωmm and improved the SS of the MOSFETs. For the device with the p⁺ layer, the SS was ~560 mV/dec, the on-resistance (R_on) was 39 Ωmm, and the threshold voltage (V_th) was 3.4 V. In contrast, the R_c was 5.8 Ωmm, the SS was ~1600 mV/dec, the R_on was 58 Ωmm, and the V_th was 13.7 V without the p⁺ layer. These results indicate that the p⁺ layer is necessary for the high-performance diamond MOSFETs in (001) surface.