Kang Evan S H, Kim Eunseong
Center for Supersolid and Quantum matter Research, Korea Advanced Institute of Science and Technology, Deajeon 305-701 (Korea).
Sci Rep. 2015 Feb 11;5:8396. doi: 10.1038/srep08396.
We investigated the low-temperature transport mechanism for poly[2,5-bis(3-alkylthiophen-2-yl)thieno(3,2-b)thiophene] (PBTTT). The temperature-dependent transport behavior was studied by varying the drain-source electric field and gate bias. The results suggest that low-temperature charge transport is dominated by direct tunneling at low electric fields, while field emission is prevailing for high electric fields with high carrier densities. However, the obtained barrier heights are remarkably greater than expected in a conventional field emission. We propose a simplified model of field emission through quasi-one-dimensional path with multiple barriers which shows good agreement with the results more clearly. Field emission across the domain boundaries may assist in overcoming the transport barriers induced by the interchain disorder, which results in the weak temperature dependence of conductivities and nonlinear current-voltage relation at low temperatures.
我们研究了聚2,5-双(3-烷基噻吩-2-基)噻吩并(3,2-b)噻吩的低温输运机制。通过改变漏源电场和栅极偏压来研究温度依赖的输运行为。结果表明，低温电荷输运在低电场下以直接隧穿为主，而在高电场和高载流子密度下场发射占主导。然而，所获得的势垒高度明显大于传统场发射中的预期值。我们提出了一个通过具有多个势垒的准一维路径的场发射简化模型，该模型与结果更清晰地显示出良好的一致性。跨域边界的场发射可能有助于克服由链间无序引起的输运势垒，这导致了电导率的弱温度依赖性和低温下的非线性电流-电压关系。
