Light Metals on Oxygen-Terminated Diamond (100): Structure and Electronic Properties

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• 作者：Kane M. O鈥橠onnell ; Tomas L. Martin ; Neil L. Allan
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：February 24, 2015
• 年：2015
• 卷：27
• 期：4
• 页码：1306-1315
• 全文大小：707K
• ISSN：1520-5002

文摘

Recently a lithiated C(100)-(1 脳 1):O surface has been demonstrated to possess a true negative electron affinity: that is, the conduction band minimum at the surface is lower in energy than the local vacuum level. Here we present a density functional theory study of diamond surfaces with various alkali-metal- and alkaline-earth-oxide terminations. We find a size-dependent variation of electronic surface properties that divides the adsorbates into two groups. In both cases, ether bridges are broken. Adsorption of the smaller alkali metals/alkaline earths such as lithium and magnesium leads to a significant surface dipole resulting from transfer of charge across X鈥揙鈥揅 complexes, whereas at the other extreme, cesium- and potassium-adsorbed C(100)-(1 脳 1):O surfaces exhibit conventional dipole formation between the ionic adsorbate and a negatively charged carbonyl-like surface. Sodium is intermediate. Computed surface band structures and density of states are presented, illustrating the key electronic differences between these two groups.