Electronic Transport in a Controllably Grown Carbon Nanotube-Silicon Heterojunction Array

A uniform array of a new type of heterojunction formed between carbon nanotubes and silicon is studied. The heterojunction array was controllably grown with parallel and uniform nanotubes vertically aligned to the silicon substrate using a self-organized nanopore array template. The pronounced rectifying characteristics of the heterojunction were measured with an $\mathrm{o}\mathrm{n}/\mathrm{o}\mathrm{f}\mathrm{f}$ ratio as high as ${10}^5$ at 4 V. The analysis shows a large and type-I band offset at the heterojunction. The charge transport in the nanotubes is found to be strongly coupled to and limited by the dielectric charging and polarization in the hosting alumina matrix surrounding the nanotubes.