Intersubband transitions in spherical quantum dot quantum well nanoparticle

Abstract

In this paper, we present results about electronic spectra and optical properties of one-electron spherical quantum dot-quantum well (QDQW) structure. Investigated structure consists of CdSe core surrounded by ZnS shell and caped by infinitely high electron potential barrier which can be a good model for any high enough potential barriers. This specific QDQW structure is determined by CdSe and ZnS properties (effective masses and conductive band offset) and the core size and the shell thickness. We present calculation results for one-electron ground (1s) state and the first excited (1p) state transition. For this transition we have calculated oscillator strengths and linear and third-order nonlinear intersubband optical absorption coefficients for various core and shell size i.e. different CdSe core radii and ZnS barrier thickness. Change in core and shell dimensions induces change in one-electron wave function i.e. electron energy states and localization for both 1s and 1p states. As a result, intersubband 1s–1p transition of this system is greatly dependent on the core and shell size. For very small core radii, less than 0.7 nm, and core radii over 1.5 nm the most probable intersubband transition is 1s–1p, but in the region between 0.7 and 1.5 nm core radii, transitions from 1s to other p states dominates. Investigated properties depend mostly on the core radius. These results connect the dot structure and the optical properties of this particular structure. This behavior is than an illustration of similar systems.