Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 10: Quantum Dots and Wires: Preparation and Characterization II (mainly Arsenides)

HL 10.7: Vortrag

Montag, 26. März 2012, 12:45–13:00, EW 202

Prepatterning of GaAs substrates using microsphere photolithography for the site-controlled growth of InP quantum dots — •Ulrich Rengstl, Elisabeth Koroknay, Moritz Bommer, Michael Jetter, and Peter Michler — Universität Stuttgart, Institut für Halbleiteroptik und Funktionelle Grenzflächen, Allmandring 3, D-70569 Stuttgart and Research Center SCoPE

To use quantum dots (QDs) in single photon applications, we are working on separate addressable, site-controlled QDs. For this, we generate surface potential modulations by patterning a GaAs buffer before the overgrowth in a metal-organic vapor-phase epitaxy system (MOVPE). Instead of using expensive conventional patterning techniques, such as electron beam lithography, we use microsphere photolithography for the fast and periodic patterning of large areas [1]. A hexagonal closepacked microsphere monolayer is used as an array of microlenses to focus UV light on a UV-sensitive photoresist. We obtain structures with controllable diameters of 300 to 700 nm in the photoresist, which can be used as an etching mask for isotropic wet chemical etching to generate holes in the GaAs buffer. Due to the later overgrowth of the patterned samples, it is crucial to sustain a clean surface with low roughness. This is traced by atomic force microscopy, which shows atomic steps between the holes in the (100) on-axis surface. After overgrowth we observe face-selective growth of GaAs and a preferred InP deposition inside the holes, which leads to the formation of site-controlled InP islands. This can be observed in a spatial photoluminescence mapping.

[1] W. Wu et al., Nanotechnology 18, 485302 (2007)