Gomez H, Cruz J, Milne C, Debnath T, Birdwell A G, Garratt E J, Pate B B, Rudin S, Ruzmetov D A, Weil J D, Shah P B, Ivanov T G, Lake R K, Groves M N, Neupane M R
Materials Science and Engineering Program, University of California Riverside, Riverside, California 92507, USA.
Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, California 92831, USA.
J Chem Phys. 2024 Aug 14;161(6). doi: 10.1063/5.0203185.
Diamond is a semiconductor material with remarkable structural, thermal, and electronic properties that has garnered significant interest in the field of electronics. Although hydrogen (H) and oxygen (O) terminations are conventionally favored in transistor designs, alternative options, such as silicon (Si) and germanium (Ge), are being explored because of their resilience to harsh processing conditions during fabrication. Density-functional theory was used to examine the non-oxidized and oxidized group-IV (Si and Ge)-terminated diamond (100) surfaces. The (3 × 1) reconstructed surfaces feature an ether configuration and show relative stability compared with the bare surface. Hybrid-functional calculations of the electronic properties revealed reduced fundamental bandgaps (<1 eV) and lower negative electron affinities (NEAs) than those of H-terminated diamond surfaces, which is attributed to the introduction of unoccupied Si (Ge) states and the depletion of negative charges. Furthermore, oxidation of these surfaces enhanced the stability of the diamond surfaces but resulted in two structural configurations: ether and ketone. Oxidized ether configurations displayed insulating properties with energy gaps of ∼4.3 ± 0.3 eV, similar to H-terminated diamond (100) surfaces, whereas bridged ether configurations exhibited metallic properties. Oxidization of the metallic ketone configurations leads to the opening of relatively smaller gaps in the range of 1.1-1.7 eV. Overall, oxidation induced a shift from NEAs to positive electron affinities, except for the reverse-ordered ketone surface with an NEA of -0.94 eV, a value comparable to the H-terminated diamond (100) surfaces. In conclusion, oxidized group-IV-terminated diamond surfaces offer enhanced stability compared to H-terminated surfaces and display unique structural and electronic properties that are influenced by surface bonding.
金刚石是一种具有卓越结构、热学和电学性质的半导体材料，在电子领域引起了广泛关注。尽管在晶体管设计中，氢（H）和氧（O）终端通常受到青睐，但由于硅（Si）和锗（Ge）等替代选项在制造过程中对恶劣加工条件具有耐受性，因此正在对其进行探索。密度泛函理论被用于研究未氧化和氧化的IV族（Si和Ge）终端金刚石（100）表面。（3×1）重构表面具有醚构型，与裸表面相比显示出相对稳定性。电子性质的杂化泛函计算表明，与氢终端金刚石表面相比，其基本带隙减小（<1 eV），负电子亲和势（NEA）更低，这归因于未占据的Si（Ge）态的引入和负电荷的耗尽。此外，这些表面的氧化增强了金刚石表面的稳定性，但导致了两种结构构型：醚和酮。氧化醚构型表现出绝缘性质，能隙约为4.3±0.3 eV，与氢终端金刚石（100）表面相似，而桥连醚构型表现出金属性质。金属酮构型的氧化导致在1.1 - 1.7 eV范围内打开相对较小的能隙。总体而言，氧化导致从负电子亲和势转变为正电子亲和势，但具有-0.94 eV负电子亲和势的逆序酮表面除外，该值与氢终端金刚石（100）表面相当。总之，与氢终端表面相比，氧化的IV族终端金刚石表面具有更高的稳定性，并表现出受表面键合影响的独特结构和电子性质。
