Arrays of one-dimensional metal/silicon and metal/carbon nanotube heterojunctions

Four types of one-dimensional (1D) heterojunctions, including Ag/Si, Pt6Si5/Si, Ni/CNT ( carbon nanotube) and Ag/a-CNT ( amorphous CNT), have been synthesized by combining electrochemical deposition and chemical vapour deposition, with porous membranes of anodic aluminium oxide (AAO) as templates. Each of these 1D heterojunctions consists of two different inorganic nanowires ( or nanotubes) connected end to end. Moreover, after an important improvement has been made on the AAO templates, ordered arrays of these 1D heterojunctions are obtained in the AAO templates, where the filling ratios of the 1D heterojunctions in the pores of the AAO templates are 100%. Thus, the electrical properties of individual 1D heterojunctions in the corresponding arrays can be accurately measured by conductive atomic force microscopy. As a result, it is found that, in the arrays of Ag/a-CNT 1D heterojunctions, the contact between the Ag nanowire and the a-CNT of every heterojunction is ohmic. This finding has universal significance, and so offers a wide opportunity for designing large-scale interconnections among nanowires and nanotubes.