Enhanced interface properties of diamond MOSFETs with Al2O3 gate dielectric deposited via ALD at a high temperature*

The interface state of hydrogen-terminated (C-H) diamond metal-oxide-semiconductor field-effect transistor (MOSFET) is critical for device performance. In this paper, we investigate the fixed charges and interface trap states in C-H diamond MOSFETs by using different gate dielectric processes. The devices use Al2O3 as gate dielectrics that are deposited via atomic layer deposition (ALD) at 80 degrees C and 300 degrees C, respectively, and their C-V and I-V characteristics are comparatively investigated. Mott-Schottky plots (1/C-2-V-G) suggest that positive and negative fixed charges with low density of about 10(11) cm(-2) are located in the 80-degrees C- and 300-degrees C deposition Al2O3 films, respectively. The analyses of direct current (DC)/pulsed I-V and frequency-dependent conductance show that the shallow interface traps (0.46 eV-0.52 eV and 0.53 eV-0.56 eV above the valence band of diamond for the 80-degrees C and 300-degrees C deposition conditions, respectively) with distinct density (7.8 x 10(13) eV(-1).cm(-2)-8.5 x 10(13) eV(-1).cm(-2) and 2.2 x 10(13) eV(-1).cm(-2)-5.1 x 10(13) eV(-1).cm(-2) for the 80-degrees C- and 300-degrees C-deposition conditions, respectively) are present at the Al2O3/C-H diamond interface. Dynamic pulsed I-V and capacitance dispersion results indicate that the ALD Al2O3 technique with 300-degrees C deposition temperature has higher stability for C-H diamond MOSFETs.

Automated summary

The study investigates the fixed charges and interface trap states in C-H diamond MOSFETs using different gate dielectric processes. The results show that positive and negative fixed charges are present in Al2O3 films deposited at 80 degrees C and 300 degrees C, while shallow interface traps of different densities are found at the Al2O3/C-H diamond interface for different deposition conditions. Dynamic pulsed I-V and capacitance dispersion results indicate that ALD Al2O3 technique with 300 degrees C deposition temperature has higher stability for C-H diamond MOSFETs.