Unraveling Surface Scattering Mechanisms in Hydrogen-Terminated Diamond/MoO₃ Heterostructures: A Theoretical Investigation

Surface transfer doping addresses diamond’s doping challenges by enabling a two-dimensional hole gas (2DHG) in hydrogen-terminated diamond (H-diamond) through electron transfer to high-electron-affinity acceptors, such as molybdenum trioxide (MoO 3 ). While prior studies optimized 2DHG density, the mechanisms limiting carrier mobility remain unresolved. Here, we present a theoretical framework to quantify the impact of acoustic phonon, surface roughness, and surface impurity scattering on hole mobility in H-diamond/MoO 3 heterostructure (∼10 13 cm –2 ). First-principles calculations demonstrate that surface roughness dominates mobility degradation, reducing it from 10 3 to 10 2 cm 2 /(V s) compared to phonon-only cases, while surface impurities further suppress mobility (MoO 3 and HCO 3 yield the highest and lowest mobilities of ∼220 and 166 cm 2 /(V s), respectively). Total calculated hole mobility (∼200 cm 2 /(V s)) aligns with experimental ranges, with roughness heights (Δ = 0.18–0.35 nm) and impurity densities ( n imp 2 D = 4.32 × 10 13 ⁡ cm − 2 ) identified as critical factors. These findings establish that mitigating interfacial surface roughness and suppressing adsorbates are essential for optimizing diamond-based devices, providing actionable strategies to enhance high-power diamond electronic performance.