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We report on a GaN metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) using atomic layer deposition (ALD) Al2O3 film as a gate dielectric and for surface passivation simultaneously. Compared to the conventional AlGaN/GaN HEMT of the same design, six order of magnitude smaller gate leakage current and tripled drain current at forward gate bias demonstrate the effectiveness of ALD Al2O3 as a gate dielectric. The high transconductance and high effective two-dimensional electron mobility verify the high-quality of Al2O3/AlGaN interface with low interface trap density. The Al2O3 passivation effect is also studied by sheet resistance measurement and short pulse drain characterization. [ABSTRACT FROM AUTHOR]

We demonstrate GaAs-based, metal-oxide-semiconductor field-effect transistors (MOSFETs) with excellent performance using an Al203 gate dielectric, deposited by atomic layer deposition (ALD). This achievement is very significant because Al2O3 possesses highly desirable physical and electrical properties as a gate dielectric. These MOSFET devices exhibit extremely low gate-leakage current, high transconductance, and high dielectric breakdown strength. A short-circuit, current-gain, cutoff frequency (fT) of 14 GHz and a maximum oscillation frequency (fmax) of 25.2 GHz have been achieved from a 0.65-µm gate-length device. The interface trap density (Dit) of Al2O3/GaAs is evaluated by the hysteresis of drain-source current, Ids, versus gate-source bias, Vgs, and the frequency dispersion of transconductance, gm. [ABSTRACT FROM AUTHOR]

Atomic layer deposition (ALD) grown Al2O3 has excellent bulk and interface properties on III-V compound semiconductors and is used as gate dielectric for GaAs and GaN metal-oxide-semiconductor field-effect transistors (MOSFETs). The low-temperature (LT) ALD technology enables us to fabricate 100 nm MOS structures on GaAs, defined by nanoimprint lithography. The electrical characterization of these nanostructured dielectrics demonstrates that the bulk oxide films and the oxide-GaAs interfaces are of high quality even in nanometer scale. The submicron gate length GaAs MOSFET formed by LT-ALD and lift-off process shows well-behaved transistor characteristics. This GaAs MOSFET process is ready to scale the gate length below 100 nm for ultra-high-speed or THz transistor applications. [ABSTRACT FROM AUTHOR]