Fabrication and Optical Properties of Strain-free Self-assembled Mesoscopic GaAs Structures

Abstract

We use a combined process of Ga-assisted deoxidation and local droplet etching to fabricate unstrained mesoscopic GaAs/AlGaAs structures exhibiting a high shape anisotropy with a length up to 1.2 μm and a width of 150 nm. We demonstrate good controllability over size and morphology of the mesoscopic structures by tuning the growth parameters. Our growth method yields structures, which are coupled to a surrounding quantum well and present unique optical emission features. Microscopic and optical analysis of single structures allows us to demonstrate that single structure emission originates from two different confinement regions, which are spectrally separated and show sharp excitonic lines. Photoluminescence is detected up to room temperature making the structures the ideal candidates for strain-free light emitting/detecting devices.

Imaging the electrostatic landscape of unstrained self-assemble GaAs quantum dots

“…The samples were grown by solid-source molecular beam epitaxy (MBE) using a commercial setup (Karl-Eberl MBE Komponenten) following a recipe reported previously [5]. First, we carried out a Ga-assisted deoxidation followed by a local Ga-droplet etching process.…”

“…It is worth pointing out that the initial hole is smaller than the mount observed at the surface by AFM. The development of the hole during filling has been systematically studied by Silva et al [5] and hole and capping parameters have been taken from this work.…”

“…GaAs-based unstrained semiconductor quantum dots have been established as a promising alternative to self-assembled strain-driven quantum dots in the last decades [1][2][3][4][5]. The common fabrication approach is the in situ or ex situ patterning of a GaAs or AlGaAs surface followed by an overgrowth to create a quantum dot structure [1,3,[6][7][8].…”

“…In this work, Kelvin probe force microscopy (KPFM) is used to directly probe the electrostatic properties of mesoscopic GaAs dot structures (MGS) defined by a local droplet etching [5,14]. We obtain a clear signature of the MGS with omitted top barrier and cap (see figure 1) in the KPFM image with a lower surface potential in the middle of the structure.…”

Scanning Tunneling Measurements in Membrane-Based Nanostructures: Spatially-Resolved Quantum State Analysis in Postprocessed Epitaxial Systems for Optoelectronic Applications

“…Embedded quantum dots and quantum wells of monolithic (epitaxial) semiconductor layers, 54 used for single-electron transistors, 55 narrow line light emitters, 56 and spintronics 57 can also be grown on sacrificial layers. Thickness limitations of some devices, which can range up to 100−200 nm could be overcome by the growth of simplified (thinner) structures, where active layers would be placed in order to enhance their response under STS conditions.…”