Direct Interband Light Absorption in Strongly Prolated Ellipsoidal Quantum Dots' Ensemble.

K G Dvoyan,D B Hayrapetyan,E M Kazaryan

doi:10.1007/s11671-008-9209-2

Abstract

Within the framework of adiabatic approximation, the energy levels and direct interband light absorption in a strongly prolated ellipsoidal quantum dot are studied. Analytical expressions for the particle energy spectrum and absorption threshold frequencies in three regimes of quantization are obtained. Selection rules for quantum transitions are revealed. Absorption edge and absorption coefficient for three regimes of size quantization (SQ) are also considered. To facilitate the comparison of obtained results with the probable experimental data, size dispersion distribution of growing quantum dots by the small semiaxe in the regimes of strong and weak SQ by two experimentally realizing distribution functions have been taken into account. Distribution functions of Lifshits–Slezov and Gaussian have been considered.

Highlights

Development of the novel growth techniques, such as the Stranski–Krastanov epitaxial method etc., makes possibleInvestigations of the optical absorption spectrum of various semiconductor structures are a powerful tool for determination of many characteristics of these systems: forbidden band gaps, effective masses of electrons and holes, their mobilities, dielectric permittivities, etc
To facilitate the comparison of obtained results with the probable experimental data, size dispersion distribution of growing quantum dots (QDs) by the small semiaxe in the regimes of strong and weak size quantization (SQ) by two experimentally realizing distribution functions have been taken into account
We have studied the absorption of a system consisting of semiconductor QDs having identical dimensions

Summary

Introduction

Development of the novel growth techniques, such as the Stranski–Krastanov epitaxial method etc., makes possible. The problem is reduced to the determination of separate energy states of the electron and hole It follows from the geometrical form of a QD that the particle motion along the radial direction occurs more rapidly than along the Z-direction. The consideration of the electron–hole interaction leads to the fact that in the spectrum of the interband optical absorption each line corresponding to given values of m transforms into a set of closely spaced lines corresponding to different values of m0 In this regime of SQ, the absorption coefficient has the form. In the case of strong SQ with account of general size distribution function P(u), we obtain for the absorption coefficient corresponding formula:. :In the case of and weak SQ k3 1⁄4 with account of general size distribution function P(u), we obtain for the absorption coefficient corresponding formula: n;nr qffiffiffiffiffiffiffiffi1ffiffiffiffiffiffiffiffiffiffiffiffiffi k23 þ 4k1k2

Discussion

Conclusion