Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 39: Impurities/amorphous semiconductors

HL 39.2: Talk

Thursday, March 29, 2007, 12:30–12:45, H14

Influence of doping and codoping on the electronic and optical properties of Si nanocrystallites — •Luis Ramos, Jürgen Furthmüller, and Friedhelm Bechstedt — Friedrich-Schiller-Universität Jena, Institut für Festkörpertheorie und -optik, Max-Wien-Platz 1 D-07743 Jena, Germany

Quantum confinement in Si nanocrystallites (NCs) leads to interesting optical and electronic properties that can be useful in optoelectronics, photovoltaics, and nanoelectronics. Since doping is a fundamental process in semiconductors, investigations have been performed to establish the doping efficiency in Si NCs in comparison with bulk. Recent experiments confirm that codoping with group-III and group-V can enhance the intensity of luminescence in Si NCs by preventing radiationless Auger recombinations, which are the main problem in shallow-impurity doping in Si NCs. Experiments usually refer to an ensemble of Si NCs with a size and shape distribution, what can make the interpretation of the results more difficult. On the other hand, theoretical methods can be used to investigate the electronic properties and optical transitions of a single Si NC.[1] We perform ab initio calculations for doped and codoped Si NCs, which are based on density-functional theory and generalized-gradient approximation to study their electronic and optical properties. The formation energy of the impurities, electronic structure and optical spectra, and radiative lifetimes for doped and codoped Si NCs are discussed.[1] L.E. Ramos, J. Furthmüller, and F. Bechstedt, Appl. Phys. Lett. 87, 143113 (2005); Phys. Rev. B 72, 045351 (2005); Phys. Rev. B 70, 033311 (2004).