Molecular Circuits for Optoelectronics utilizing Carbon Nanotubes

应在三端器件中测量单个分子的光电导，作为波长、源极/漏极电压、第三端的栅极电压以及4.2 K至室温范围内的温度的函数。通过自组装过程，分子将与两个单壁碳纳米管（SWNT）接触，SWNT充当分子的介观源极/漏极接触。有机电路SWNT分子-SWNT？具有几百纳米的长度，这允许通过标准电子束光刻接触器件，并进而图案化局部侧栅极。通过向侧栅极施加电压，分子中电子的能级可以静电地改变。对于分子的光激发，我们利用脉冲，wavelengthtunable激光系统，它允许测量接近分子的吸收带的光电导。使用脉冲激光系统而不是连续波激光器最大限度地减少了接触中的加热效应对分子传输特性的影响。此外，在单壁碳纳米管-分子接触区域的原子重排预计只发挥较小的作用相比，金接触。为了提供直接的实验证据，只有一个分子的特点，我们计划运输测量光开关分子，如偶氮苯或芪，也对金属蛋白质。光开关在光激发下会发生构象变化，这使得研究分子构象对光开关输运性质的影响成为可能。同时，分子构象的成功和可逆转换表明，只有一个分子被连接和光电特征。另一方面，蛋白质允许通过扫描探针显微镜验证其存在。

The photo-conductance across a single molecule shall be measured in a three-terminal device as a function of the wavelength, the source/drain voltage, a gate voltage on the third terminal and the temperature in the range of 4.2 K and room temperature. The molecules will be contacted by two single wall carbon nanotubes (SWNTs), which act as mesoscopic source/drain contacts to the molecule, via a self-assembly process. The organic circuit ¿SWNT-molecule-SWNT¿ has a length of several hundreds of nanometers, which allows contacting the device by standard e-beam lithography and in turn, patterning of local side-gates. By applying voltages to the side-gates, the energy levels of the electrons in the molecule can be altered electrostatically. For the photo-excitation of the molecule we utilize a pulsed, wavelengthtunable laser system, which allows measuring the photo-conductance close to the absorption bands of the molecule. Using a pulsed laser system instead of a continuous wave laser minimizes the influence of heating effects in the contacts on the transport properties of the molecule. In addition, atomic rearrangements in the SWNT-molecule contact region are expected to play only a minor role as compared to gold contacts. In order to give direct experimental evidence that only one molecule is being characterized, we plan transport measurements on photo-switchable molecules, such as azobenzene or stilbene, and also on metalloproteins. Photo-switches exhibit a conformational change induced by photo-excitation, which allows studying the effect of molecular conformation on the transport properties. At the same time, a successful and reversible switching of the molecular conformation demonstrates that just one molecule is being connected and characterized optoelectronically. Proteins, on the other hand, allow verification of their presence by scanning probe microscopy.