Cao Jien, Wang Qian, Dai Hongjie
Department of Chemistry and Laboratory for Advanced Materials, Stanford University, California 94305, USA.
Nat Mater. 2005 Oct;4(10):745-9. doi: 10.1038/nmat1478. Epub 2005 Sep 4.
Single-walled carbon nanotubes have shown a wealth of quantum transport phenomena thus far. Defect-free, unperturbed single-walled carbon nanotubes with well behaved or tunable metal contacts are important for probing the intrinsic electrical properties of nanotubes. Meeting these conditions experimentally is non-trivial owing to numerous disorder and randomizing factors. Here we show that approximately 1-microm-long fully suspended single-walled carbon nanotubes grown in place between metal contacts afford devices with well defined characteristics over much wider energy ranges than nanotubes pinned on substrates. Various low-temperature transport regimes in true-metallic, small- and large-bandgap semiconducting nanotubes are observed, including quantum states shell-filling, -splitting and -crossing in magnetic fields owing to the Aharonov-Bohm effect. The clean transport data show a correlation between the contact junction resistance and the various transport regimes in single-walled-carbon-nanotube devices. Furthermore, we show that electrical transport data can be used to probe the band structures of nanotubes, including nonlinear band dispersion.
迄今为止，单壁碳纳米管已展现出丰富的量子输运现象。具有良好或可调节金属接触的无缺陷、未受干扰的单壁碳纳米管对于探究纳米管的本征电学性质至关重要。由于存在众多无序和随机因素，通过实验满足这些条件并非易事。在此我们表明，在金属接触之间原位生长的约1微米长的完全悬浮单壁碳纳米管所构成的器件，在比固定在衬底上的纳米管宽得多的能量范围内具有明确的特性。在真正的金属、小带隙和大带隙半导体纳米管中观察到了各种低温输运状态，包括由于阿哈罗诺夫 - 玻姆效应在磁场中量子态的壳层填充、分裂和交叉。纯净的输运数据表明了单壁碳纳米管器件中接触结电阻与各种输运状态之间的相关性。此外，我们表明电输运数据可用于探测纳米管的能带结构，包括非线性能带色散。
