The electrical properties of the diamond field effect transistor

200 µm thick free-standing polycrystalline diamond film has been grown by microwave plasma chemical vapor deposition (MPCVD) method. The nucleation surface of diamond is characterized by Raman scattering, scanning electron microscopy (SEM) and atomic force microscopy (AFM) method. AFM and SEM results indicate the nucleation surface is quite smooth with a mean surface roughness (RMS) of about 10 nm. Raman scattering result indicates of high quality nucleation diamond film. A diamond field effect transistor is fabricated on hydrogenated diamond nucleation surface, using standard lithographic procedures. Device with aluminum (Al) gate electrode, to form Schottky barrier with diamond, as well as Au source and drain electrodes to form ohmic contact with diamond, operates as effective enhancement-mode metal-semiconductor field-effect transistors at room temperature, showing clear modulation of channel current.