Slow Growth of CdSe Nanocrystals in Glass and Their Refractive Index Change

Abstract

The refractive index change of semiconductor nanocrystals must be known when designing precision optical components based on semiconductor nanocrystals. In this study, Kramers-Kronig transformation has been used to compute the linear refractive index change of cadmium selenide (CdSe) nanocrystals embedded in glass. Classical theory and numerical computation of Kramers-Kronig relation have been given and explained in detail. CdSe nanocrystals have been grown in borosilicate glass by using melting, rapid-cooling, and heat treatment procedure. Compared to the production studies of semiconductor nanocrystals in borosilicate glass in the literature, the growth temperature of CdSe nanocrystals in glass has been decreased and their growth time has been extended. In other words, a slow growth method has been performed to form pure CdSe nanocrystals in glass. The quantum size effect has been observed at their optical absorption spectra. Surface and longitudinal optical phonon modes of CdSe nanocrystals have been measured by using Raman spectroscopy. The refractive index change has been found as ~1.36x10^-4 for CdSe nanocrystals with a diameter of ~3.93 nm.