Boron-Doped Diamond MOSFETs With Gradual Channel Doping Density

Abstract

The growth of gradual boron-doped diamond epitaxial layer was achieved by microwave plasma chemical vapor deposition (MPCVD). Secondary ion mass spectrometry (SIMS) results show that the effective doping concentration range is from 10 ¹⁵ cm ⁻³ to 10 ¹⁹ cm ⁻³ , and the doping layer thickness is about 45 nm. Boron-doped diamond Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) was prepared by using 300 ° C atomic layer deposition (ALD) Al ₂ O ₃ as gate dielectric. The maximum output current and transconductance of the device reach -1.2 mA/mm and $127~\mu $ S/mm, respectively, both of which are higher than the reported. Meanwhile, the device has a low threshold voltage of 3.3 V. We suggested that the low ohmic contact resistance (R $_{\text {C}}\text {)}$ induced by the high doping density on the sample surface and the thin doping layer thickness contribute to these high device performances.