Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 19: Quantum dots and wires: Optical properties II

HL 19.5: Talk

Tuesday, March 28, 2006, 18:15–18:30, HSZ 01

Electric field induced photoluminescence quenching in CdSe nanocrystal doped SiO₂ on Si — •Helmut Karl, Alexander Achtstein, and Bernd Stritzker — Institut für Physik, Universität Augsburg, D-86135 Augsburg, Germany

Buried CdSe nanocrystals were synthesized by sequential ion implantation of Cd and Se in 500 nm thick thermally grown SiO₂ on p-doped silicon. The formation of the CdSe nanoclusters was initiated by a post-implantation thermal annealing step. Then an optically semitransparent thin Au gate electrode was evaporated on top of the SiO₂ forming a MOS capacitor structure. The embedded surface near CdSe nanocrystals show efficient steady state CdSe bandedge photoluminescence when excited by a cw-HeCd laser at a wavelength of 442 nm at room temperature. The silicon substrate was electrically contacted by indiffusion of an evaporated Al thin film. With this structure we observe strong electric field induced photoluminescence quenching when a voltage is applied between the Au gate electrode and the silicon substrate for temperatures between 10 K and room temperature. PL quenching of more than 80 % was found for an electric field variation between 0 and +/- 4x10⁷ V/m. CV-characteristics in conjunction with the electric field dependence of the PL quenching will be discussed.