Single-Electron Transistor in Strained Si/SiGe Heterostructures

TL;DR

This paper demonstrates the fabrication and operation of a single-electron transistor in strained Si/SiGe heterostructures using split gate technology, showing controllable quantum dots and Coulomb blockade at low temperatures.

Contribution

It introduces a split gate technique for forming tunable quantum dots in Si/SiGe heterostructures and shows that Schottky gate issues are not inherent to these materials.

Findings

Single-electron operation achieved below 1K

Gate leakage currents are well controlled

Schottky gate problems are not intrinsic to Si/SiGe heterostructures

Abstract

A split gate technique is used to form a lateral quantum dot in a two-dimensional electron gas of a modulation-doped silicon/silicon-germanium heterostructure. e-beam lithography was employed to produce split gates. By applying negative voltages to these gates the underlying electron gas is depleted and a lateral quantum dot is formed, the size of which can be adjusted by the gate voltage. We observe single-electron operation with Coulomb blockade behavior below 1K. Gate leakage currents are well controlled, indicating that the recently encountered problems with Schottky gates for this type of application are not an inherent limitation of modulation-doped Si/SiGe heterostructures, as had been speculated.