B离子注入引起的金刚石薄膜体积膨胀现象

离子注入是获得金刚石N型或P型导电材料的有效途径之一。然而,离子注入对金刚石的晶格结构有破坏作用,造成金刚石薄膜体积的膨胀。本文对B离子注入合成Ib型金刚石薄膜后体积膨胀现象进行了研究,分析了引起体积膨胀的可能因素及原因。     

Electronic transport properties of phenylacetylene molecular junctions

Electronic transport properties of a kind of phenylacetylene compound— (4-mercaptophenyl)-phenylacetylene are calculated by the first-principles method in the framework of density functional theory and the nonequilibrium Green's function formalism. The molecular junction shows an obvious rectifying behaviour at a bias voltage larger than 1.0 V. The rectification effect is attributed to the asymmetry of the interface contacts. Moreover, at a bias voltage larger than 2.0 V, which is not referred to in a relevant experiment [Fang L, Park J Y, Ma H, Jen A K Y and Salmeron M 2007 Langmuir 23 11522], we find a negative differential resistance phenomenon. The negative differential resistance effect may originate from the change of the delocalization degree of the molecular orbitals induced by the bias.