Temperature dependence of the Hall effect in pentacene field-effect transistors: Possibility of charge decoherence induced by molecular fluctuations
Temperature dependence of the Hall effect in pentacene field-effect transistors: Possibility of charge decoherence induced by molecular fluctuations
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DOI：
10.1103/physrevb.85.035313
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发表时间：
2012-01-17
影响因子：
3.7
通讯作者：
Takeya, J.
中科院分区：
文献类型：
--
作者：
Uemura, T.;Yamagishi, M.;Takeya, J.
测量并五苯单晶和薄膜场效应晶体管的霍尔效应的温度依赖性。在室温下，无论样品的载流子迁移率和亚阈值特性如何，所有样品的逆霍尔系数1/R（H）在每个栅极电场下都超过场致电荷密度Q 2倍。违反1/R（H）等于Q的带输运模型，过量的1/R（H）不再测量电荷量，使得结果可能指示由于稍微降低的电荷相干性而导致的电磁耦合不足。在较低温度下，1/R（H）与Q的偏差逐渐减小，接近带输运行为。有趣的是，对于所测量的五个样品，包括多晶和单晶并五苯膜，偏差的程度是普遍的。结果表明，室温附近的分子涨落对基态电子态有影响。
Temperature dependence of the Hall effect is measured for both single-crystal and thin-film field-effect transistors of pentacene. At room temperature, the inverse Hall coefficient 1/R(H) exceeds field-induced charge density Q by a factor of 2 at each gate-electric field for all the samples, regardless of their charge-carrier mobility and detailed subthreshold properties. Violating the band-transport model that 1/R(H) equals to Q, the excess 1/R(H) does not measure the charge amount anymore so that the result possibly indicates insufficient electromagnetic coupling due to somewhat reduced charge coherence. At lower temperatures, the deviation of 1/R(H) from Q gradually diminishes to approach the band-transport behavior. Interestingly, the degree of the deviation has been universal for the measured five samples, including both polycrystal and single-crystal pentacene films. The result suggests that significant molecular fluctuation near room temperature can affect the fundamental electronic state.