Master thesis project (announced 20141128): Simulation, fabrication, and characterization of synthetic opals towards solarcell applications Contacts: Min Yan, Optics and Photonics, Department of Materials and Nano Physics, School of ICT, KTH (Electrum, Kista) Yanting Sun, Semiconductor Materials, Department of Materials and Nano Physics, School of ICT, KTH (Electrum, Kista) Project description: Natural opals exhibit stunning colors [1]. The colors are due to periodic arrangements of silica spheres with diameters at a few hundreds of nanometers. Synthetic opals can nowadays be fabricated in lab through selfassembling of silica nano spheres. Modern techniques exist which allow such synthetic opals to be fabricated with a very fine crystalline quality [2]. The concerned project will utilize such synthetic opals as periodic templates for making periodic semiconductor nanostructures towards solarcell applications. The candidate is expected to design and optimize geometrical parameters of opals through numerical calculations. The objective is to get desired lightrefraction property of the designed 3D periodic structure, for achieving better trapping of incident light across appropriate wavelength ranges. Finiteelement method based on COMSOL Multiphysics will be extensively used for that purpose. There is a possibility for the candidate to fabricate the corresponding opal structure in the Electrum lab. Subsequent optical characterization of the fabricated structure can be also carried out. Depending on the candidate’s interest, the actual project can be narrowed to one specific portion of the procedure described above. (a) (b) (c) Fig. 1. (a) Natural opal [1]; (b) Optical micrograph of an opal made in Electrum lab, KTH (image courtesy of X. Chen); (c) A scanningelectron micrograph of a labfabricated opal structure [2]. References: [1]. http://en.wikipedia.org/wiki/Opal [2]. Y.A. Vlasov, X.Z. Bo, J.C. Sturm, D.J. Norris, “Onchip natural assembly of silicon photonic bandgap crystals,” Nature 414, 289 (2001).