Spectroscopy of sub-wetting layer states in InAs/GaAs quantum dot bi-layer systems

Abstract

The density of states for InAs/GaAs quantum dot (QDs) bi-layer arrays placed between two AlGaAs barriers is studied by means of photoluminescence (PL) excitation, resonant PL and time-resolved PL. By varying the excitation energy from above the AlGaAs band gap to values resonant with the QD energies, the energy of states in each layer including the wetting layer, corresponding localized states, defect states and QD states is determined. The creation of asymmetric pairs of quantum dots caused by interlayer coupling is traced starting from the case of weakly correlated systems represented by bi-layer QD arrays with a thick GaAs spacer layer (50 monolayers) to the case of fully correlated systems with a GaAs spacer (30 monolayers). Different mechanisms of carrier relaxation related to the density of states below the barrier and interlayer coupling are explored.

Cooperative Effects in the Photoluminescence of (In,Ga)As/GaAs Quantum Dot Chain Structures

“…The appearance of the dip on the dependences for the detection energies lower than E 0 (see Fig. 7 ) can be attributed to the coupling of longitudinal optical phonons with confined electrons and holes in QDs and to the presence of deep levels allowing the holes tunnel to these states even at low temperatures [ 34 ]. The states of deep levels are closer to the states of larger QDs.…”

Вплив термічної активації носіїв заряду на температурні залежності темнового струму, фотопровідність та фотолюмінесценцію гетероструктур In0,4Ga0,6As/GaAs з квантовими точками

“…КТ InAs в GaAs матрицi використанi як активне середовище iнфрачервоних лазерiв [1], як матерiал для оптичних пристроїв збереження iнформацiї [2] та новiтнiх одноелектронних [3] i квантово-iнформацiйних пристроїв [4]. Велику кiлькiсть публiкацiй було присвячено вивченню оптичних властивостей InGaAs/GaAs гетероструктур з КТ методами спектроскопiї поглинання [5,6], фотолюмiнесценцiї (ФЛ) [7,8], комбiнацiйного розсiювання свiтла [9].…”