Influence of Metal Gate Electrodes on Electrical Properties of Atomic-Layer-Deposited Al-Rich HfAlO/Ga2O3 MOSCAPs

• As the p-type doping beta-Ga2O3 is absent up to now, metal gate (MG) stacks with high work functions are expected to benefit the fabrication of normally-OFF beta-Ga2O3 transistors. In this article, the electrical characteristics of beta-Ga2O3 metal-electrode-gated metal-oxidesemiconductor (MOS) deviceswith Al-rich HfAlO dielectrics and different MG stacks (Ni, Au, Pt, and Ti) are evaluated. The interface state density (Dit) of HfAlO/ beta-Ga2O3 interface is characterized based on the frequency-dependent capacitance-voltage (C-V) and photo-assisted deep ultraviolet (DUV) C-V measurements. An average Dit of 4.45 x 10(11) eV(-1)cm(-2) is extracted from the photo-assisted (deep UV) C-V measurement, while a large amount of border traps, negative fixed charges, and deep traps is also induced at the oxide layer and/or HfAlO/beta-Ga2O3 interface. Then, this article investigates the evaluations of Ti, Ni, Au, and Pt as candidate MGs for beta-Ga2O3 MOS using Al-rich HfAlO as gate dielectric. The obvious flat-band voltage (V-FB) shift and gate leakage variation are observed in beta-Ga2O3 capacitors with different MG solutions, indicating that HfAlO dielectric combined with Ni, Au, and Pt MGs is promising to facilitate some beneficial modifications of normally-OFF beta-Ga2O3 transistors, while Ti electrode ismore suitable for normally-ON beta-Ga2O3 transistors. This article provides an additional practical guideline for choosing the appropriate MG stacks and potential gate dielectric to the development of normally-OFF Ga2O3 transistors.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

Gallium oxide; HfAlO; high-k (HK) gate dielectrics; metal gate (MG)

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