2D Amorphous GaO_X Gate Dielectric for β-Ga₂O₃ Field-Effect Transistors

Abstract

Appropriate gate dielectrics must be identified to fabricate metal–insulator–semiconductor field-effect transistors (MISFETs); however, this has been challenging for compound semiconductors owing to the absence of high-quality native oxides. This study uses the liquid-gallium squeezing technique to fabricate 2D amorphous gallium oxide (GaOX) with a high dielectric constant, where its thickness is precisely controlled at the atomic scale (monolayer, ∼4.5 nm; bilayer, ∼8.5 nm). Beta-phase gallium oxide (β-Ga2O3) with an ultrawide energy bandgap (4.5–4.9 eV) has emerged as a next-generation power semiconductor material and is presented here as the channel material. The 2D amorphous GaOX dielectric is combined with a β-Ga2O3 conducting nanolayer, and the resulting β-Ga2O3 MISFET is stable up to 250 °C. The 2D amorphous GaOX is oxygen-deficient, and a high-quality interface with excellent uniformity and scalability forms between the 2D amorphous GaOX and β-Ga2O3. The fabricated MISFET exhibits a wide gate-voltage swing of approximately +5 V, a high current on/off ratio, moderate field-effect carrier mobility, and a decent three-terminal breakdown voltage (∼138 V). The carrier transport of the Ni/GaOX/β-Ga2O3 metal–insulator–semiconductor (MIS) structure displays a combination of Schottky emission and Fowler–Nordheim (F–N) tunneling in the high-gate-bias region at 25 °C, whereas at elevated temperatures it shows Schottky emission and F–N tunneling in the low- and high-gate-bias regions, respectively. This study demonstrates that a 2D GaOX gate dielectric layer can be produced and incorporated into an active channel layer to form an MIS structure at room temperature (∼25 °C), which enables the facile fabrication of MISFET devices.

Comprehensive understanding of electron mobility and superior performance in sub-10 nm DG ML tetrahex-GeC2 n-type MOSFETs

“…29–32 To enhance current channel materials, approaches include device modifications like vertical structures and improved gate/dielectric stacks. 33–48 Nonetheless, the pursuit of new 2D semiconductors with optimal band gaps, higher mobility, and improved air stability remains essential. 49–52…”

A high-breakdown-voltage β-Ga2O3 nanoFET with a beveled field-plate structure

“…16 Nanoscale β-Ga 2 O 3 FETs, Schottky diodes, β-Ga 2 O 3 integrated with other two-dimensional (2D) materials, including hexagonal boron nitride (h-BN) and graphene, MOSFETs, metal–semiconductor FETs (MESFETs), and other electronic and power devices based on β-Ga 2 O 3 nanolayers have been reported. 17–20 Nanoscale β-Ga 2 O 3 can also be combined with Si and other 2D van der Waals materials to create heterostructure electrical devices. Kim et al fabricated a β-Ga 2 O 3 junction FET via van der Waals bonding of β-Ga 2 O 3 and a WSe 2 flake, which exhibited a high rectifying ratio and breakdown voltage.…”