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HL: Halbleiterphysik

HL 23: Poster II

HL 23.52: Poster

Mittwoch, 24. März 1999, 14:00–18:00, Z

Optical properties of CdS quantum dots embedded in an organic matrix — •A. Milekhin¹, M. Friedrich¹, L. Sweshnikowa², S. Repinskii², and D.R.T. Zahn¹ — ¹Institut f"ur Physik, Technische Universit"at, D-09107 Chemnitz — ²Institute of Semiconductor Physics, Novosibirsk, 630090, Russia

We present the results of ultra-violet, Raman and infrared spectroscopical studies of CdS quantum dots formed by the Langmuir-Blodgett technique. The average size of the quantum dots of 3-6 nm estimated from the analysis of ultra-violet absorption spectra is in a good agreement with results of electron microscopy measurements. The small size leads to localisation of optical phonons in quantum dots and a quantisation of the phonon spectrum. It results in a frequency shift of the fundamental optical phonons toward lower frequency. The red shift of the LO phonons in CdS quantum dots caused by quantum size effect was observed by Raman spectroscopy. The surface optical (SO) modes were investigated by infrared spectroscopy. The influence of the surrounding media on the frequency position of the SO modes is discussed.