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 (MoO3). 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/MoO3 heterostructure (∼1013 cm–2). First-principles calculations demonstrate that surface roughness dominates mobility degradation, reducing it from 103 to 102 cm2/(V s) compared to phonon-only cases, while surface impurities further suppress mobility (MoO3 and HCO3 yield the highest and lowest mobilities of ∼220 and 166 cm2/(V s), respectively). Total calculated hole mobility (∼200 cm2/(V s)) aligns with experimental ranges, with roughness heights (Δ = 0.18–0.35 nm) and impurity densities (nimp2D=4.32×1013⁡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.