Theory of shot noise in high-current space-charge-limited field emission
Theory of shot noise in high-current space-charge-limited field emission
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DOI：
10.1103/physrevb.77.115351
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发表时间：
2008-03-01
影响因子：
3.7
通讯作者：
Koh, W. S.
中科院分区：
文献类型：
--
作者：
Wu, L.;Ang, L. K.;Koh, W. S.
本文研究了高电流空间电荷限制（SCL）场发射的电子散粒噪声，包括间隙内发射的隧道电子的量子分配和库仑相关效应。法诺因子（伽马）是在经典、量子和相对论范围内的各种施加电压、间隙间距和电子脉冲长度下计算的。研究发现，空间电荷平滑效应（在热电子发射中观察到）对于高电流场发射不再有效，因为空间电荷场会增加势垒，从而降低量子分配程度（较大的伽玛）。然而，由于库仑斥力和隧道电子之间的交换相关势的结合，纳米间隙中SCL场发射的散粒噪声可能会被抑制，其中间隙内电子的动力学是通过使用量子平均场模型来处理的。当电子束的脉冲长度远小于间隙渡越时间时，库仑相关性可以忽略。讨论了可能的实验设置，以便观察有或没有空间电荷效应的场发射散粒噪声抑制。
This paper studies the electron shot noise of high current space-charge limited (SCL) field emission, including the effects of both quantum partitioning and Coulomb correlation of the emitted tunneling electrons inside a gap. The Fano factor (gamma) is calculated over a wide range of applied voltages, gap spacings, and electron pulse lengths in classical, quantum and relativistic regimes. It is found that the effect of space charge smoothing (observed in thermionic emission) is no longer valid for high current field emission, as the space charge field will increase the potential barrier and thus decrease the degree of quantum partitioning (larger gamma). However, the shot noise of SCL field emission in a nanogap may be suppressed due to the combination of Coulomb repulsion and exchange-correlation potential among the tunneling electrons, where the dynamics of the electrons inside the gap are treated by using a quantum mean field model. Coulomb correlation can be ignored when the pulse length of the electron beam is much smaller than the gap transit time. Possible experimental settings are discussed in order to observe the shot noise suppression of field emission with and without the space charge effects.