Engineering carrier confinement potentials in 1.3-μm InAs/GaAs quantum dots with InAlAs layers: Enhancement of the high-temperature photoluminescence intensity

Abstract

We describe an optical study of structures consisting of an InAlAs-GaAs strained buffer layer and an InAlAs-InGaAs composite strain-reducing layer designed to modify the confining potential of 1.3-μm InAs/GaAs quantum dots (QDs). With increasing (decreasing) InAlAs (InGaAs) thickness in the strain-reducing layer grown above the QDs, the integrated photoluminescence (PL) intensity of the QD ground-state transition increases dramatically and the emission wavelength decreases slightly from 1.36 to 1.31 μm. The enhancement of PL efficiency is temperature dependent, being much greater above 200 K. A maximum enhancement of 450 is achieved at room temperature. This improvement of the high-temperature PL efficiency should lead to a significant improvement in the characteristics of 1.3-μm InAs/GaAs QD lasers.

Structural studies of a combined InAlAs–InGaAs capping layer on 1.3-μm Inas/GaAs quantum dots

“…This leads to a degradation of the laser performance, notably an increased temperature sensitivity due to thermal carrier escape. Instead of using a conventional InGaAs or GaAs capping layer, an InAlAs-InGaAs combined two-level capping layer has been developed to increase the confinement of the InAs QDs for advanced laser applications [12,13]. Liu et al [12] have demonstrated that the room-temperature ground-state photoluminescence (PL) intensity of 1.3-mm InAs/GaAs QDs is increased substantially, by a factor of approximately 450, when the InAlAs layer thickness was increased from 1.5 to 6.0 nm.…”

“…Instead of using a conventional InGaAs or GaAs capping layer, an InAlAs-InGaAs combined two-level capping layer has been developed to increase the confinement of the InAs QDs for advanced laser applications [12,13]. Liu et al [12] have demonstrated that the room-temperature ground-state photoluminescence (PL) intensity of 1.3-mm InAs/GaAs QDs is increased substantially, by a factor of approximately 450, when the InAlAs layer thickness was increased from 1.5 to 6.0 nm. A large energy separation between the ground and the first-excited state of 108 meV has been obtained by this growth technique [14].…”

Far-Infrared/THz Photodetector with Self-assembled Quantum Dots

“…Note that the electronic energy states of conduction band in the quantum dot and/or dot-in-a-well structure, and hence the detection wavelengths can be modulated by bandgap engineering including the control of quantum dot size, well width, and the location of the dot later in the well. It can be also performed utilizing different barrier layers [10][11][12]. …”

The influence of the quantum‐confined Stark effect on InGaN/AlGaN quantum dots

“…For technical application it is favorable to achieve single‐photon emission in the short‐wavelength range at even more elevated temperatures. In order to increase the carrier confinement an often reported concept is to sandwich the QDs between additional barriers with a higher band gap . In II–VI materials, the utilization of additional barriers has already resulted in single‐photon emission at room temperature .…”