Comment on "Conductance oscillations periodic in the density of a one-dimensional electron gas"
Comment on "Conductance oscillations periodic in the density of a one-dimensional electron gas"
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DOI：
10.1103/physrevlett.63.1893
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发表时间：
1989-10
影响因子：
8.6
通讯作者：
van Houten H;Beenakker
中科院分区：
文献类型：
--
作者：
van Houten H;Beenakker
在最近的一封信中，斯科特-托马斯等人。宣布了在窄的Si反型层的密度中周期性地电导振荡的实验发现。提出了钉扎电荷密度波的解释。1> 2我们提出了一个替代的单电子解释这个显着的效果，基于隧道的库仑阻塞的概念（由与单个电子的隧道相关的充电能量引起）。Likharev 3和安曼、Müllen和Ben-Jacob 4从理论上研究了通过对两个串联隧道结之间的区域进行电容充电（通过栅极端子）来消除库仑阻塞的可能性。他们发现，由于充电能量的调制，这种器件的零偏置电导呈现出周期性峰值，这是栅极电压的函数。我们提出，通过参考文献1中的通道的电流受到隧穿势垒的限制，势垒由两个主要的散射中心构成，它们限定了一维通道的一部分（见图1）。我们通过电容C1和Ca来描述两个隧道势垒。由于位于两个势垒之间的区域中的电子数量必然是一个整数，因此在该区域和连接到宽电子气库的相邻区域之间会出现电荷不平衡，从而产生静电势差。当栅极电压变化时，所得费米能级差Δ e/τ在±eA之间以π模式振荡，其中A~ e/2C是具有电荷e/2的有效电容C-Ci+ Ca上的电压降。单电子充电能量e2/2C保持费米能级差，直到Δ E>-±Δ。然后，单个电子转移到（或从）两个势垒之间的区域的能量消失，因此库仑阻塞被消除，电导在低温T和源漏电压V（keT/e，Δ）下显示出未激活的最大值。3> 4· 5费米能级随栅压的变化而振荡，从而导致一系列电导峰。振荡的周期性对应于在形成隧道势垒的两个散射中心之间的区域中添加单个电子，因此在实验中振荡在密度-Δ s中是周期性的。这种单电子隧穿机制也解释了所观察到的电导最小值的激活以及对磁场的不敏感性。112电容
In a recent Letter, Scott-Thomas et al.'announced the experimental discovery of conductance oscillations periodic in the density of a narrow Si Inversion layer. An Interpretation in terms of pinned charge-density waves was suggested. 1> 2 We propose an alternative single-electron explanation of this remarkable effect, based upon the concept of the Coulomb blockade of tunneling (arising from the charging energy associated with the tunneling of a single electron). Likharev3 and Amman, Müllen, and Ben-Jacob4 have studied theoretically the possibility of removing the Coulomb blockade by capacitive charging (by means of a gate terminal) of the region between two tunnel junctions in series. They found that the zero-bias conductance of such a device exhibits periodic peaks äs a function of gate voltage, due to the modulation of the charging energy. We propose that the current through the channel in Ref. l is limited by tunneling through potential barriers constituted by two dominant scattering centers which delimit a segment of the one-dimensional channel (see Fig. 1). We describe the two tunnel barriers by capacitances C\and Ca. Because the number of electrons localized in the region between the two barriers is necessarily an integer, a Charge imbalance, and hence an electrostatic potential difference, arises between this region and the adjacent regions connected to wide-electron-gas reservoirs. As the gate voltage is varied, the resulting Fermi-level difference Δ£/τ oscillates in a sawtooth pattern between±eA, where A~ e/2C is the voltage drop over the effective capacitance C—Ci+ Ca with Charge e/2. The single-electron charging energy e2/2C maintains the Fermi-level difference, until ΔΕ>—±Δ. Then the energy for the transfer of a single electron to (or from) the region between the two barriers vanishes, so that the Coulomb blockade is removed, and the conductance shows an unactivated maximum at low temperatures T and source-drain voltages V (keT/e, Κ^ Δ). 3> 4· 5 The oscillation of the Fermi energy äs the gate voltage is varied thus leads to a sequence of conductance peaks. The periodicity of the oscillations corresponds to the addition of a single electron to the region between the two scattering centers forming the tunnel barriers, so that the oscillations are periodic in the density—äs in the experiment. This single-electron tunneling mechanism also explains the observed activation of the conductance minima, and the insensitivity to a magnetic field. ll2 The capacitance