Embedded Semiconductor Quantum Dots - Current Overview

This review paper focuses on semiconductor quantum dots (QDs) embedded inside semiconductor heterostructures prepared by Metalorganic Vapor Phase Epitaxy (MOVPE) technology and based on our contribution in [1]. Semiconductor direct-bandgap materials have much higher energy conversion efficiency than the light emission from atoms/molecules in a glass matrix or from most other light sources, but they have a broad band or multimode light emission spectra. QDs created and embedded inside semiconductor heterostructures can fundamentally improve the quality of emitted light spectrum, temperature dependencies and efficiency of emission.QDs exhibit unique electronic and optical properties, intermediate between those of bulk semiconductors and discrete atoms or molecules. The reason for this is that the size of QDs is comparable with the de Broglie wavelength of an electron in a crystal. Electrons (and holes) inside QDs behave differently from that found in a "bulk" material. The most important difference is that inside the QDs, electrons (and holes) can occupy only discrete energy levels due to strong localization. The position of energy levels depends mainly on the smallest dimension of a QD. Applications include QD lasers for integrated silicon photonics and quantum computing, QD LEDs for highly efficient solid-state lighting, QDs for intermediate band solar cells and multi-exciton generation and QDs for bio-medical labeling, imaging, targeted drug delivery, sensing, and therapy.