Memory effects in optically active CdSe nanocrystal doped MOS structures

We present a first study of the synthesis of CdSe nanocrystals embedded in 50 nm thick thermally grown SiO2 on p-type silicon by sequential ion implantation of Cd (30 keV) and Se (26 keV) followed by a rapid thermal annealing step. A metal-oxide-semiconductor (MOS) capacitor structure was fabricated by evaporation of an optically transparent thin Au gate electrode on top of the nanocluster doped SiO2 layer. The observed band edge emission of CdSe is fully intensity tuneable by applying a high electric field over the MOS structure. Strong hysteretic electric field enhancement and quenching of the photoluminescence (PL) was observed when sweeping the electric field strength between ±1 MV/cm. Further an electro optical memory effect was observed in this device and investigated upon its long time stability. Possible mechanisms for this behavior are discussed.