I. E. Kozin

Dynamics of Carrier Relaxation in Self-Assembled Quantum Dots

Relaxation of hot carriers in quantum dots (QDs) has been widely discussed since the beginning of research of self-assembled QDs. Understanding of carrier relaxation mechanisms is important from both the practical and the fundamental points of view. The carrier relaxation in QDs controls, to a great extent, the efficiency of luminescence from ground radiative states. This is highly important, for example, for laser applications of QD structures where the relaxation must be as fast as possible [1–3]. On the other hand, QD lasers in the mid-IR range can be devised on inter-sub-band transitions if a relatively slow carrier relaxation takes place [4]. To reach these limiting points, a careful study of various processes of carrier relaxation should be done.

Spin Quantum Beats in the Stokes Shifted Photoluminescence of InP Quantum Dots

Quantum beats observed in the photoluminescence kinetics of a single layer of self-assembled quantum dots in a magnetic field are studied as a function of the Stokes shift between the excitation and photoluminescence frequencies in the wide range of Stokes shifts from 7 to 70 meV. The quantum beats are attributed to beats between the fine-structure states of electron-hole pairs.

Quantum Beats in Photoluminescence of InP Quantum Dots in Electric Field

The photoluminescence (PL) kinetics of heterostructures with InP self-assembled quantum dots are studied under quasi-resonant pulse excitation in the presence of an external electric field. An oscillatory behavior of the PL kinetics is shown to arise due to quantum beats of the radiative states. A model of the coherent excitation of nonresonant PL is proposed.

LO phonon resonances in photoluminescence spectra of InP self-assembled quantum dots in electric field

Strong longitudinal optical (LO) phonon resonances were observed in the photoluminescence (PL) spectra of InP self-assembled quantum dots (QDs) in an external electric field. They are shown to arise from fast LO phonon-assisted relaxation of hot carriers and become observable when the PL is suppressed by nonradiative relaxation of the carriers from excited states of the QDs.

Carrier relaxation dynamics in self-assembled quantum dots studied by artificial control of nonradiative losses

Abstract : A novel technique to study carrier relaxation dynamics based on the artificial control of nonradiative losses by an external electric field is proposed. A clear evidence of phonon assisted relaxation as the main relaxation mechanism of hot electron-hole pairs in InP self-assembled quantum dots is found by the proposed method. Efficient one step relaxation processes with emission of acoustic and optical phonons are observed. These findings give new and important insight into the interaction of the electron-hole pairs in quantum dots with the phono subsystem.

Unusual temperature behavior of the photoluminescence of the InP and InGaAs quantum dots under quasi-resonance excitation

Abstract An “unusual” thermal behavior was observed in the photoluminescence of self-assembled III–V quantum dots under quasi-resonant excitation. The effect manifests itself as a prominent increase of the PL intensity at elevated temperatures, both in Stokes and anti-Stokes parts of spectra. This effect is observable in both InP and InGaAs quantum dots. A simple general model of spectral diffusion is proposed to explain this phenomenon.