Dependence of Modulation Amplitude on Electron Density in Unidirectional Lateral Superlattices: The Effect of the Thickness of the Two-dimensional Electron Gas

TL;DR

This study investigates how the amplitude of a unidirectional periodic potential in a 2DEG varies with electron density, revealing a dependence influenced by the 2DEG thickness and measurement method.

Contribution

It demonstrates the dependence of modulation amplitude on electron density and 2DEG thickness, providing insights into the electronic response in heterostructure systems.

Findings

Amplitude decreases with increasing electron density.

Rate of amplitude change varies with measurement method.

Thickness of the 2DEG significantly affects the response.

Abstract

The amplitude V_0 of unidirectional periodic potential modulation introduced by a surface grating into a two-dimensional electron gas (2DEG) formed at AlGaAs/GaAs heterointerface is measured as a function of electron density n_e by analyzing commensurability oscillation of the magnetoresistance. The electron density is varied either by applying a bias to a metallic back gate or by illumination. The amplitude decreases with increasing density, with the rate |dV_0/dn_e| roughly an order of magnitude larger for the former method. The result is interpreted in terms of the rate, dE_1/d(delta E_c), of the change in the first subband level E_1 in response to the variation of the conduction-band edge delta E_c above the heterointerface. The rate crucially depends on the thickness of the 2DEG.