Tunable Frohlich polarons in organic single-crystal transistors
Tunable Frohlich polarons in organic single-crystal transistors
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DOI：
10.1038/nmat1774
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发表时间：
2006-12-01
期刊：
影响因子：
41.2
通讯作者：
Morpurgo, A. F.
中科院分区：
文献类型：
--
作者：
Hulea, I. N.;Fratini, S.;Morpurgo, A. F.
在有机场效应晶体管（FET）中，电荷在有机半导体的表面附近、在与电介质的界面处移动。过去，电荷载体的微观运动性质（决定器件性能）与有机半导体的质量有关。最近，人们发现附近的电介质也有意想不到的强大影响。造成这种影响的机制尚不清楚。为了研究这些机制，我们研究了通过有机单晶场效应晶体管与不同的栅极绝缘体的运输。我们发现，随着绝缘体介电常数的增加，迁移率的温度依赖性从类金属演化到类绝缘。这种现象是占一个二维Frohlich极化子模型，定量描述了我们的观察，并表明，增加介电极化率的结果在交叉从弱到强极化子耦合制度。这代表了我们对通过有机晶体管传输的理解向前迈出了相当大的一步，并确定了对器件性能有很大影响的微观物理过程。
In organic field-effect transistors (FETs), charges move near the surface of an organic semiconductor, at the interface with a dielectric. In the past, the nature of the microscopic motion of charge carriers-which determines the device performance-has been related to the quality of the organic semiconductor. Recently, it was discovered that the nearby dielectric also has an unexpectedly strong influence. The mechanisms responsible for this influence are not understood. To investigate these mechanisms, we have studied transport through organic single-crystal FETs with different gate insulators. We find that the temperature dependence of the mobility evolves from metallic-like to insulating-like with increasing dielectric constant of the insulator. The phenomenon is accounted for by a two-dimensional Frohlich polaron model that quantitatively describes our observations and shows that increasing the dielectric polarizability results in a crossover from the weak to the strong polaronic coupling regime. This represents a considerable step forward in our understanding of transport through organic transistors, and identifies a microscopic physical process with a large influence on device performance.