Conductance fluctuations near the localized-to-extended transition in narrow Si metal-oxide-semiconductor field-effect transistors.
Conductance fluctuations near the localized-to-extended transition in narrow Si metal-oxide-semiconductor field-effect transistors.
复制标题
窄硅金属氧化物半导体场效应晶体管中局部到扩展转变附近的电导波动。
DOI：
10.1103/physrevb.36.8015
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Bishop
中科院分区：
文献类型：
--
作者：
Kastner;Kwasnick;Licini;Bishop
一个统一的理论图景已经出现，可以解释无序的一维电阻的电导波动。在零温度T下，如果局域化长度ξ小于样品长度L，则电流通过共振隧穿进行，随着费米能量的变化，电导会产生指数级的波动。另一方面，如果ξ> L，波动的大小总是e2 /h。随着T的提高，对于L> ξ，波动最初保持指数级大，但这是一维声子辅助跳变的结果。在更高的T下，非弹性扩散长度L in扮演着样本长度的角色，当L in变得和局域化长度一样短时，状态就会离域。对于高于这个局部到扩展转变的温度，在长度为L的样品中，电导的波动始终为e2 /h阶。我们介绍了在硅金属氧化物半导体场效应晶体管中窄（~ 70 nm）反转层的实验结果。在低温度下，在低电导下有指数大的波动，在高电导下有e2 /h的波动。结果表明，在低电导情况下，电流对费米能、温度和源漏电压的依赖关系可以用一维声子辅助跳变来解释。样品太长，无法观察到共振隧穿。然而，指出在有限的温度范围内没有观测到一些预测的特征。在高电导下，在长度为L in的样品中，波动的大小为e2 /h。对发生局域到扩展跃迁时的电导值进行估计：即，在长度为L in的样本中，电导及其波动均为~ e2 /h的值。
A unified theoretical picture has emerged to explain the fluctuations in the conductance of disordered, one-dimensional resistors. At zero temperature T, and if the localization length ξ is shorter than the sample length L, current is carried by resonant tunneling which gives rise to exponentially large conductance fluctuations as the Fermi energy is varied. On the other hand, if ξ> L, the fluctuations are always of size e 2/h. As T is raised, the fluctuations at first remain exponentially large for L> ξ, but are the result of one-dimensional phonon-assisted hopping. At still higher T, the inelastic diffusion length L in plays the role of sample length, and when L in becomes as short as the localization length the states become delocalized. For temperatures above this localized-to-extended transition, the fluctuations of conductance are always of order e 2/h in a sample of length L in. We present the results of experiments on narrow (∼ 70 nm) inversion layers in Si metal-oxide-semiconductor field-effect transistors. At low T there are exponentially large fluctuations at low conductance and e 2/h fluctuations at high conductance. It is shown that the dependence of current on Fermi energy, temperature, and source-drain voltage for low conductance can be explained by one-dimensional phonon-assisted hopping. The samples are too long to observe resonant tunneling. It is pointed out, however, that several predicted features are not observed in the limited temperature range studied. At high conductance the fluctuations are of size e 2/h in a sample of length L in. An estimate is made of the value of the conductance at which the localized-to-extended transition occurs: That is, the value at which the conductance and its fluctuations are both∼ e 2/h in a sample of length L in.