Integration of colloidal nanocrystals in epitaxial semiconductor nanostructures

• Applicants: Dr. Detlef Schikora; Professorin Dr. Ulrike K. Woggon
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2005 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5454056

The project is aimed at the development of tunable, photo-stable, and positioned nanoemitters for integrated optics and electronics. The enormous potential of colloidal nanocrystals concerning tunability shall be combined with the device-compatible technique of molecular beam epitaxy (MBE). An epitaxial growth technique shall be developed where externally, wet-chemically produced colloidal nanocrystals are incorporated into epitaxial heterostructures. Compared to the well-established Stranski-Krastanow epitaxial growth, the proposed approach reflects a change in the paradigm: quantum dots can be epitaxially grown without any strain-requirements from lattice-matched material combinations. Thermodynamic limitations are no longer valid, a great variety of semiconductor material combinations and even metal-semiconductor combinations become possible. As first test subjects we plan (i) the overgrowth of CdSe nanocrystals by wide-gap II-VI materials, (ii) the use of colloidal nanocrystals as a chemical carrier for doping of light-emitting ions (e.g. ZnSe:Mn) and (iii) the overgrowth of InAs nanocrystals with GaAs, (iv) the growth on both flat and patterned substrates. The mechanism of epitaxial growth and overgrowth on colloidal nanocrystals will be explored as a function of density, shape and crystalline structure of the nanocrystals with the aim to realise epitaxial cap layers of high structural perfection providing compatibility with further growth towards integrated optics.

• DFG Programme: Research Grants