In situ reduction of charge noise in GaAs/AlGaAs Schottky-gated devices

TL;DR

This paper demonstrates that using an insulated electrostatic gate significantly reduces charge noise in GaAs/AlGaAs devices by decreasing electron leakage, with the noise spectrum shifting from Lorentzian to 1/f type, independent of DX centers.

Contribution

It introduces a method to suppress charge noise in GaAs/AlGaAs devices using an insulated gate, supported by simulations and experimental comparisons.

Findings

Charge noise is strongly suppressed by an insulated gate.

The noise spectrum shifts from Lorentzian to 1/f type after suppression.

DX centers are not the primary source of charge noise.

Abstract

We show that an insulated electrostatic gate can be used to strongly suppress ubiquitous background charge noise in Schottky-gated GaAs/AlGaAs devices. Via a 2-D self-consistent simulation of the conduction band profile we show that this observation can be explained by reduced leakage of electrons from the Schottky gates into the semiconductor through the Schottky barrier, consistent with the effect of "bias cooling". Upon noise reduction, the noise power spectrum generally changes from Lorentzian to $1/f$ type. By comparing wafers with different Al content, we exclude that DX centers play a dominant role in the charge noise.