3A.4 Final.2025

Abstract
In this study we demonstrate that enhancement-mode behavior (Vₜₕ > 0) is achievable for β-Ga2O3 FinFET using a Fin width 𝑾𝑭𝑰𝑵≤0.5 μm and doping concentration 𝑵𝒅≤1×10¹⁶ cm⁻3. Breakdown voltage and output/transfer characteristics are calculated by using Drift-Diffusion methodology calibrated by experiments. We found that the metal work function (∅𝒎𝒔), dielectric constant (κ), and unintentional negative interface charge density (-Qf) at the β-Ga2O3/dielectric interface significantly impact Vₜₕ, with a high ∅𝒎𝒔 being necessary for enhancement mode operation. To achieve 5kV breakdown, a 𝑾𝑭𝑰𝑵 of 200 nm requires a fin thickness (𝑻𝑭𝑰𝑵) of 0.8 μm, a 𝑾𝑭𝑰𝑵 of 400 nm requires 𝑻𝑭𝑰𝑵> 1.2 μm, and a 𝑾𝑭𝑰𝑵 > 600 nm requires 𝑻𝑭𝑰𝑵 > 2 μm. From 𝑾𝑭𝑰𝑵 of 200 nm to 400 nm, DIBL (drain induced barrier lowering, i.e. Vₜₕ /Vds) increases by 300%, while from 400 to 600 nm, it rises by only 100%. -Qf increases breakdown voltage. Finally, β-Ga2O3 fin structures were fabricated to optimize etch profile.