Abstract: The wide bandgap semiconductor β-Ga₂O₃ possesses an ultra-wide band gap of 4.85 eV and substantial critical electrical field of 8 MV/cm ^[1-2]. However, it is characterized by a significantly low thermal conductivity ^[3] and challenges in achieving p-type doping ^[4]. Diamond, often hailed as the ultimate semiconductor, exhibits the highest thermal conductivity among wide-bandgap semiconductors. Nevertheless, achieving n-type doping in diamond remains a challenge. Consequently, the integration of β-Ga2O3 and diamond heterostructures emerges as an appealing solution. Although there have been some relevant experimental reports ^[5-7], The relevant theoretical research is still lacking, necessitating further investigations and studies.

We construct a β-Ga₂O₃/diamond heterogeneous supercell and comprehensively investigate its geometric structure and electronic properties using first-principles calculations. Previous reports have indicated that the presence of hydrogen (H) terminals reduces the electronic affinity of diamond, making it a negative electronic affinity ^[8]. To investigate the impact of H terminals on the electronic affinity of the diamond and the band alignment at the interface, we have established the β-Ga₂O₃/diamond supercells with H and without the H terminal on the diamond surface. In the former case, we selected β-Ga₂O₃ with 100A and 100B terminals to examine the influence of different Ga₂O₃ surfaces on the interface band offsets. All the interface models possess a clean band gap, indicating compliance with the ECR requirements ^[9-10]. Based on this foundation, we use the core-level method to discuss the band alignment. The VBO calculated without H terminal model is 2.89 eV, which results align well with experimental values (~2.93 eV) ^[11-13]. Notably, the model incorporating H terminals displays a larger band step. The H terminal model with 100A β-Ga₂O₃ terminal manifests a VBO of 4.52 eV, while the model with 100B β-Ga₂O₃ terminal manifests a VBO of 3.92 eV. 

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