High quality Al2O3/(100) oxygen-terminated diamond interface for MOSFETs fabrication

In this letter, we report on the improvement of gate controlled Al₂O₃/(100) boron doped (B-doped) oxygen-terminated diamond (O-diamond) Metal Oxide Semiconductor Capacitors using 40 nm thick Al₂O₃ deposited by Atomic Layer Deposition at 380 °C and then annealed at 500 °C in vacuum conditions. The high quality of Al₂O₃ and an Al₂O₃/diamond interface is verified thanks to electrical measurements and Transmission Electron Microscopy (TEM) measurements. A density of interface states lower than 10¹² eV^-1 cm^-2 is measured from the flat-band regime to the depletion regime. The shift of the flat-band voltage and the leakage current through the oxide are significantly reduced in good agreement with the mono-crystalline character of the Al₂O₃ layer revealed by TEM.