Gao Jia, Loo Yueh-Lin
Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Phys Chem Chem Phys. 2014 Jun 14;16(22):10861-5. doi: 10.1039/c4cp00665h.
In this study, we have elucidated the interactions between ozone and carbon nanotubes by monitoring the characteristics of field-effect transistors based on polymer-sorted, large-diameter semiconducting carbon nanotubes. The drain-source current of these transistors initially increases with ozone exposure and then it progressively decreases with increasing exposure beyond 3 min. This non-monotonic dependence of the drain-source current can be ascribed to two competing processes. At short ozone exposure, p-doping of carbon nanotubes dominates; the drain-source current thus increases as a result of increasing hole concentration. This effect is most evidenced in a progressive threshold voltage shift towards positive voltages with increasing exposure to ozone. At extended ozone exposure, chemical oxidation of carbon nanotubes instead dominates. The drain-source current decreases as a result of decreasing hole mobility. This effect manifests itself in a monotonic decrease in the mobility of these devices as a function of ozone exposure.
在本研究中，我们通过监测基于聚合物分类的大直径半导体碳纳米管的场效应晶体管的特性，阐明了臭氧与碳纳米管之间的相互作用。这些晶体管的漏源电流最初随着臭氧暴露而增加，然后在暴露超过3分钟后随着暴露时间的增加而逐渐降低。漏源电流的这种非单调依赖性可归因于两个相互竞争的过程。在短时间臭氧暴露下，碳纳米管的p型掺杂占主导；因此，由于空穴浓度增加，漏源电流增大。随着臭氧暴露增加，阈值电压逐渐向正电压偏移，这一效应最为明显。在长时间臭氧暴露下，碳纳米管的化学氧化则占主导。由于空穴迁移率降低，漏源电流减小。这种效应表现为这些器件的迁移率随臭氧暴露呈单调下降。
