Linear and nonlinear intersubband optical properties of Si quantum dot embedded in oxide, nitride, and carbide matrix

Abstract

In this paper we study the linear and nonlinear intersubband optical properties of a nanocrystalline singly charged Si semiconductor quantum dot surrounded by an amorphous matrix of silicon dioxide, silicon nitride, and silicon carbide. A finite barrier height is considered at the interface of the dot and matrix. We also consider the effect of self-energy associated with the surface polarization due to the charging of the dot and the size dependent dielectric constant of the dot. The effect of the surrounding matrix is investigated on the linear and nonlinear absorption coefficient, refractive index changes, nonlinear susceptibility, and photoelectric cross section. Using the effective mass approximation (EMA) results are obtained for different dot radii, photon energies, and intensities. It is noted that an increase in barrier height due to the surrounding matrix leads to blueshift in peak positions of absorption coefficients and refractive index change.