Individual charge traps in silicon nanowires: Measurements of location, spin and occupation number by Coulomb blockade spectroscopy

TL;DR

This study investigates charge traps in silicon nanowires using Coulomb blockade spectroscopy, revealing their locations, spin states, and occupation dynamics, with implications for quantum device stability.

Contribution

The paper introduces a model to accurately identify trap locations and properties in silicon nanowires, linking anomalies to arsenic dopant states and trap spin characteristics.

Findings

Traps are located near or inside the wire.

Anomalies linked to arsenic dopant states.

Trap spins are characterized via Zeeman shift.

Abstract

We study anomalies in the Coulomb blockade spectrum of a quantum dot formed in a silicon nanowire. These anomalies are attributed to electrostatic interaction with charge traps in the device. A simple model reproduces these anomalies accurately and we show how the capacitance matrices of the traps can be obtained from the shape of the anomalies. From these capacitance matrices we deduce that the traps are located near or inside the wire. Based on the occurrence of the anomalies in wires with different doping levels we infer that most of the traps are arsenic dopant states. In some cases the anomalies are accompanied by a random telegraph signal which allows time resolved monitoring of the occupation of the trap. The spin of the trap states is determined via the Zeeman shift.