Li Chenxi, Oliveira Eliezer F, Biswas Abhijit, Puthirath Anand B, Zhang Xiang, Pramanik Atin, Garratt Elias J, Neupane Mahesh R, Pate Bradford B, Birdwell Anthony Glen, Ivanov Tony G, Terlier Tanguy, Vajtai Robert, Ajayan Pulickel M
Department of Materials Science and Nanoengineering, Rice University, Houston, Texas 77005, United States.
School of Sciences, Department of Physics and Meteorology, São Paulo State University (Unesp), Bauru, São Paulo 17033-360, Brazil.
ACS Appl Mater Interfaces. 2023 Aug 23;15(33):39980-39988. doi: 10.1021/acsami.3c07102. Epub 2023 Aug 9.
Diamond surface functionalization has received significant research interest recently. Specifically, H-termination has been widely adopted because it endows the diamond surface with negative electron affinity and the hole carrier is injected in the presence of surface transfer dopants. Exploring different functional groups' attachment on diamond surfaces and their impact on the electronic structure, using wet and dry chemical approaches, would hence be of interest in engineering diamond as a semiconductor. Here, we report the functionalization of the H-terminated diamond surface with nitrogen and sulfur heteroatoms. Surface characterization of functionalized diamond surfaces shows that these groups are well-distributed and covalently bonded to diamonds. Four chemical functional groups (-SH, -S-S-, -S-O, and -S=O) were found on the sulfurized diamond surface, and two groups (-NH and =NH) upon amination. We also report co-functionalization of surface with N and S (N-S), where sulfurization promotes sequential amination efficiency with reduced exposure time. Electrical measurement shows that heteroatom-modified diamond surfaces possess higher conductivity than H-terminated diamonds. Density functional theory (DFT) shows that upon functionalization with various N/S ratios, the conduction band minimum and valence band maximum downshift, which lowers the bandgap in comparison to an H-terminated diamond. These observations suggest the possibility of heteroatom functionalizations with enhanced surface electrical conductivity on the diamond that are useful for various electronic applications.
近年来，金刚石表面功能化受到了广泛的研究关注。具体而言，氢终止（H-termination）已被广泛采用，因为它赋予金刚石表面负电子亲和性，并且在存在表面转移掺杂剂的情况下会注入空穴载流子。因此，采用湿法和干法化学方法探索不同官能团在金刚石表面的附着及其对电子结构的影响，对于将金刚石作为半导体进行工程化应用具有重要意义。在此，我们报道了用氮和硫杂原子对氢终止的金刚石表面进行功能化。功能化金刚石表面的表征表明，这些基团分布均匀且与金刚石共价键合。在硫化金刚石表面发现了四种化学官能团（-SH、-S-S-、-S-O和-S=O），胺化后发现了两种官能团（-NH和=NH）。我们还报道了表面的氮和硫共功能化（N-S），其中硫化促进了连续胺化效率，同时缩短了暴露时间。电学测量表明，杂原子修饰的金刚石表面比氢终止的金刚石具有更高的导电性。密度泛函理论（DFT）表明，在用各种氮/硫比例进行功能化后，导带最小值和价带最大值下移，与氢终止的金刚石相比，这降低了带隙。这些观察结果表明，在金刚石上进行杂原子功能化以增强表面导电性是可能的，这对于各种电子应用非常有用。
