Wafer-Scale Epitaxial Modulation of Quantum Dot Density

TL;DR

This paper presents a method using molecular beam epitaxy to control quantum dot density across wafers, enabling precise patterning and ultra-low noise QD growth for quantum photonics applications.

Contribution

The authors demonstrate a universal technique to modulate quantum dot density during epitaxy, achieving patterned distributions while maintaining high quality.

Findings

Density modulation between 1 and 10 QDs/μm² achieved

Pattern periods range from millimeters to hundreds of microns

Method enables growth of ultra-low noise QDs on 3-inch wafers

Abstract

Precise control of the properties of semiconductor quantum dots (QDs) is vital for creating novel devices for quantum photonics and advanced opto-electronics. Suitable low QD-density for single QD devices and experiments are challenging to control during epitaxy and are typically found only in limited regions of the wafer. Here, we demonstrate how conventional molecular beam epitaxy (MBE) can be used to modulate the density of optically active QDs in one- and two- dimensional patterns, while still retaining excellent quality. We find that material thickness gradients during layer-by-layer growth result in surface roughness modulations across the whole wafer. Growth on such templates strongly influences the QD nucleation probability. We obtain density modulations between 1 and 10 QDs/${\mu}m^{2}$ and periods ranging from several millimeters down to at least a few hundred microns. This novel method is universal and expected to be applicable to a wide variety of different semiconductor material systems. We apply the method to enable growth of ultra-low noise QDs across an entire 3-inch semiconductor wafer.