Analysis of homogeneity of 2D electron gas at decreasing of electron density

TL;DR

This study examines how the capacitance of a 2D electron gas system varies with gate voltage, revealing a capacitance drop at lower electron densities primarily due to increased resistance, while the system remains homogeneous at low temperatures.

Contribution

It provides an analysis linking capacitance drop to resistance effects and confirms homogeneity of the 2D electron gas at low temperatures.

Findings

Capacitance drops sharply with decreasing electron density.

Resistance of the 2D gas mainly causes the capacitance drop.

System remains homogeneous down to low temperature conductivity.

Abstract

We investigate the gate voltage dependence of capacitance of a system gate - 2D electron gas (C-Vg). The abrupt drop of capacitance at decreasing concentration was found. The possible reasons of this drop, namely inhomogeneity of electron density distribution and serial resistance of 2D electron gas are discussed. Simultaneous analysis of gate voltage dependences of capacitance and resistance has shown that in heavily doped 2D systems the main role in the drop of capacitance at decreasing concentration plays the resistance of 2D gas. It is found that the investigated systems remains homogeneous down to the low temperature conductivity about (10^-2-10^-3)e^2/h.