Electric-field-dependent spectroscopy of charge motion using a single-electron transistor

TL;DR

This study uses electric-field-dependent spectroscopy on a single-electron transistor to identify the location of charge fluctuators, revealing they are near the oxide surface rather than in the silicon or tunnel barriers.

Contribution

It demonstrates a method to determine the position of charge fluctuators using controlled electric fields and a specialized transistor design.

Findings

Charge fluctuators are near the oxide surface.

Fluctuators are not in the silicon layer or tunnel barriers.

The method distinguishes fluctuator locations based on electric-field response.

Abstract

We present observations of background charge fluctuators near an Al-AlO_x-Al single-electron transistor on an oxidized Si substrate. The transistor design incorporates a heavily doped substrate and top gate, which allow for independent control of the substrate and transistor island potentials. Through controlled charging of the Si/SiO_2 interface we show that the fluctuators cannot reside in the Si layer or in the tunnel barriers. Combined with the large measured signal amplitude, this implies that the defects must be located very near the oxide surface.