Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas

Details Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas

2010-07-29

arxiv.org/abs/1007.5308v2

Phys. Rev. B 82, 155111 (2010)

Physics

Condensed Matter

Mesoscale and Nanoscale Physics

7 pages, 6 figures; revised discussion of the zero density limit

Scientific paper

10.1103/PhysRevB.82.155111

In electronic devices where a two-dimensional electron gas (2DEG) comprises one or both sides of a plane capacitor, the resulting capacitance $C$ can be larger than the "geometric capacitance" $C_g$ determined by the physical separation $d$ between electrodes. This larger capacitance is known to result from the Coulomb correlations between individual electrons within the low density 2DEG, which lead to a negative thermodynamic density of states (negative compressibility). Experiments on such systems generally operate in the regime where the average spacing between electrons $n^{-1/2}$ in the 2DEG is larger than $d$, and these experiments observe $C > C_g$ by only a few percent. A recent experiment [1], however, has observed $C$ larger than $C_g$ by almost 40% while operating in the regime $nd^2 << 1$. In this paper we argue that at $nd^2 << 1$ correlations between the electronic charge of opposite electrodes become important. We develop a theory of the capacitance for the full range of $nd^2$. We show that, in the absence of disorder, the capacitance can be $4d/a$ times larger than the geometric value, where $a << d$ is the electron Bohr radius. Our results compare favorably with the experiment of Ref. [1] without the use of adjustable parameters.

Affiliated with

Also associated with

No associations

Rating

Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-452622