Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.90: Poster

Thursday, March 17, 2011, 18:00–21:00, P4

Towards site controlled growth of InAs quantum dots on patterned GaAs by microsphere photolithography — •Ulrich Rengstl, Elisabeth Koroknay, Robert Roßbach, Michael Jetter, and Peter Michler — Institut für Halbleiteroptik und Funktionelle Grenzflächen, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany

To use quantum dots (QDs) in single photon applications, like quantum information processing, we are working on separate addressable, site controlled QDs. For this, we generate surface potential modulations by patterning the GaAs surface before the overgrowth in a metal-organic vapor-phase epitaxy system (MOVPE). Conventional patterning techniques, such as electron beam lithography or site controlled surface oxidation using scanning tunneling microscopy, have the disadvantage of high time consumption. A faster method for prepatterning a large surface uses microsphere photolithography [1]. For partial exposure of UV-sensitive photoresist, we use a hexagonal close-packed microsphere monolayer as an array of microlenses to focus UV-light. We obtained structures with controllable diameters of 300 to 700 nm in the photoresist, which can be used as an etching mask for wet chemical etching to generate holes in the GaAs surface. After this, various steps of post etch cleaning and oxide removal are necessary to obtain a GaAs buffer with low defect density and high optical quality after the following overgrowth. The prepatterning also leads to an increased accumulation of deposited InAs inside the holes, which supports island growth.

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