Electronic Structure Analysis of Single‐Crystal Diamond on Iridium Heteroepitaxy: A Density Functional Theory Study

Abstract By utilizing the Bias‐Enhanced Nucleation (BEN) process, pre‐deposited diamond nuclei on an iridium (Ir) substrate promote the heteroepitaxial growth of single‐crystal diamond. In contrast, direct growth on Ir substrates without the BEN process leads to the formation of polycrystalline diamond, and the underlying mechanisms remain unclear. To address this issue, an electronic structure‐based matching method is proposed to compare the density of states (DOS) profiles of carbon atoms between bulk diamond and diamond/Ir heterojunctions. The results reveal significant differences between the DOS profiles of carbon atoms at the surface of a one‐layer diamond film on Ir and those of bulk diamond. In comparison, the DOS profiles of carbon atoms at the surface of an eight‐layer diamond film on Ir closely resemble those of bulk diamond. Thus, carbon atoms directly grown on the Ir substrate do not exhibit diamond‐like electronic characteristics and may instead form various carbon allotropes. By contrast, pre‐deposited diamond nuclei with consistent crystal orientations facilitate diamond growth on the Ir substrate in a manner similar to homoepitaxy, thereby enhancing the feasibility of single‐crystal diamond heteroepitaxy.