Semiconductor Quantum Dot Heterostructures Growth And Applications

The reduction of dimensionality of the carrier motion in quantum nanostructures brings new, interesting effects in semiconductor physics. In addition, it opens an exciting possibility of improving the device performance. It has been predicted that the delta-function like density of states inherent for the objects with three-dimensional quantum confinement (quantum dots) should lead to the decrease in threshold current density, and improvement of its temperature stability (for semiconductor injection lasers when the quantum dot heterostructures are used as an active region). In the present work we discuss the synthesis of InAs/GaAs quantum dots by using self-organization phenomena at the initial stages of strained layer heteroepitaxy. We show that the driving force for the island formation is strain accumulating during the deposition of the lattice mismatched material. Quantum dot size and shape are presented and their optical properties are discussed. The characteristics of quantum dot injection lasers are shown. The ways to reduce threshold current density and improve its temperature stability are demonstrated. The band-gap and strain engineering are shown to be effective tools for controlling the quantum dot optical emission range.