[8p-Z05-1~20] 6.2 Carbon-based thin films

▲ [8p-Z05-8] First-Principles Study on Oxidative Etching of Diamond (100) Surface

〇(M2)John Isaac Guinto Enriquez¹, Fahdzi Muttaqien², Masato Michiuchi³, Kouji Inagaki¹, Masaaki Geshi¹, Ikutaro Hamada¹, Yoshitada Morikawa¹ (1.Osaka Univ., 2.Inst. Tech. Bandung, 3.Sumitomo Elec. Ind.)

Keywords:diamond, oxidation, DFT

Precision engineering of diamond is a major technological hurdle in its novel applications because of its hardness and chemical inertness. Gaining atomic-level understanding of the mechanism of diamond (100) oxidation will lead to insights that will accelerate the development of diamond fabrication tools. In this study, we performed first-principles density functional simulations to develop a comprehensive theory of the oxidation of diamond (100) surface. Gas-phase triplet O₂ can be metastably adsorbed before undergoing intersystem crossing to singlet state and form carbonyl and epoxide groups. The more stable ether chain forms on defect-free surfaces at higher surface coverage. The desorption activation energy of CO is lesser than CO₂ for both atomically smooth surface and various defective surfaces. Preferential etching has been found along the rows perpendicular to the direction of C-dimers which are caused by the vacancy left by desorbed CO. The desorption activation energy of isolated CO agrees reasonably with existing experiment and theoretical studies. In addition, we report for the first time a wide range of activation energies caused by vacancy nucleation and surface reconstruction resulting from subsequent CO desorption which explains the unusually broad peak of the thermal desorption spectra. Single-atom-high etched trough is stabilized by dimerization and adsorption of O₂, which gives theoretical support for the observed features of diamond (100) surfaces thermally etched with dry oxygen.