Electrical field dependence of hopping conduction in self-organized carbon networks
Electrical field dependence of hopping conduction in self-organized carbon networks
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DOI：
10.1063/1.1421238
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发表时间：
2002-01-15
影响因子：
3.2
通讯作者：
Parisi, J
中科院分区：
文献类型：
--
作者：
Govor, LV;Bashmakov, IA;Parisi, J
研究了电场对多孔碳网络变程跳跃过程的影响，在ln sigma（T）与T（-1/2）成正比的范围内，其中sigma和T分别表示电导率和温度。我们发现，在附近的金属-绝缘体过渡的样品调查的场依赖性清楚地区分四个特征区域。在较低的外加电场值下，我们有欧姆电导率。在增加电场E时，电导率σ上升，首先遵循与E（n）成比例的定律ln σ（E），其中n随着与绝缘侧上的金属-绝缘体过渡的距离增加而从1.4变化到2.6。然后，在更高的电场下，电导率变成关系ln σ（E）正比于E（1.0）。在上述电场范围内确定的载流子跳跃长度的温度依赖性发展为I（T）与T（-0.9）成正比。在库仑隙中发生欧姆行为并遵守ln sigma（T）与T（-1/2）成比例的定律的温度下，由热未激活的电荷载流子在高场下引起的电导率遵守ln sigma（E）与E（-1/3）成比例。电流密度j随着ln j（E）与E（-1/6）成比例而变化。表征从低场到高场范围的转变的阈值电场的温度依赖性遵循E（th）与T（1.5）成比例。(C)2002年美国物理学会。
The influence of the electrical field on the variable range hopping process of porous carbon networks is examined in the range of validity of the law ln sigma (T)proportional toT(-1/2), where sigma and T mean electrical conductivity and temperature, respectively. We show that the field dependence of the samples investigated in the vicinity of the metal-insulator transition clearly distinguishes four characteristic regions. At low values of the applied electrical field, we have ohmic conductivity. Upon increasing the electrical field E, the electrical conductivity sigma rises, first following the law ln sigma (E)proportional toE(n), where n changes from 1.4 to 2.6 with increasing distance from the metal-insulator transition on the insulating side. Then, at higher electrical field, the conductivity turns to the relation ln sigma (E)proportional toE(1.0). The temperature dependence of the hopping length of the charge carriers, determined within the above field regime, develops as l(T)proportional toT(-0.9). At temperatures where the ohmic behavior in the Coulomb gap occurs and obeys the law ln sigma (T)proportional toT(-1/2), the electrical conductivity caused by thermally nonactivated charge carriers at high fields complies with ln sigma (E)proportional toE(-1/3). The current density j changes as ln j(E)proportional toE(-1/6). The temperature dependence of the threshold electrical field, which characterizes the transition from the low-field to the high-field range, follows E(th)proportional toT(1.5). (C) 2002 American Institute of Physics.