AlGaN Channel Field Effect Transistors with Graded Heterostructure Ohmic Contacts

Abstract

We report on ultra-wide bandgap (UWBG) Al0.75Ga0.25N channel metal-insulator-semiconductor field-effect transistors (MISFET) with heterostructure engineered low-resistance ohmic contacts. The low intrinsic electron affinity of AlN (0.6 eV) leads to large Schottky barriers at metal-AlGaN interface, resulting in highly resistive ohmic contacts. In this work, we use reverse compositional graded n++ AlGaN contact layer to achieve upward electron affinity grading, leading to a low specific contact resistance of 1.9x10-6 ohm.cm2 to n-Al0.75Ga0.25N channels (bandgap ~ 5.3 eV) with non-alloyed contacts. We also demonstrate UWBG Al0.75Ga0.25N channel MISFET device operation employing compositional graded n++ ohmic contact layer and 20 nm atomic layer deposited Al2O3 as the gate-dielectric.

References in corpus (2)

• Realization of wide electron slabs by polarization bulk doping in graded III-V nitride semiconductor alloys
• Modeling of High Composition AlGaN Channel HEMTs with Large Threshold Voltage

Cited by in corpus (5)

• Tunnel-injected sub-260 nm ultraviolet light emitting diodes
• Compositionally graded contact layers for MOCVD grown high Al-content AlGaN transistors
• Increasing the mobility and power-electronics figure of merit of AlGaN with atomically thin AlN/GaN digital-alloy superlattices
• High Breakdown Electric Field (> 5 MV/cm) in UWBG AlGaN Transistors
• Barrier Electrostatics and Contact Engineering for Ultra-Wide Bandgap AlGaN HFETs