Temperature dependence of photoluminescence spectra in InAs/GaAs quantum dot superlattices with large thicknesses

Abstract

In this report, we investigate the thermal relaxation of the photoluminescence (PL) in InAs/GaAs quantum dot superlattices with large thicknesses that have two to more than three times the critical thickness for spontaneous island formation. It is found that the linewidth first decreases and then increases with increasing temperature. In addition to thermionic emission, we suggest that carrier repopulation among quantum dots plays an important role in the PL quenching. The temperature dependence of PL peak energy following a Varshni relation was attributed to the dilation of lattice and electron-lattice interaction. The emission intensity quenches rapidly when the temperature rises to around 60 K, indicating the existence of defect-related centers in the vicinity of InAs/GaAs interfaces. In addition, we performed the measurement of the activation energy of PL quenching at different emission energy. We found that the loss mechanism of PL quenching based on the activation of electron-hole pairs from quantum dots to the adjacent barriers was difficult to explain the behavior in quantum dots with large thicknesses. In this case, we suggest that the PL quenching is dominated by the recombination through interface defects.

Exciton thermal escape in symmetric InAs quantum dots in InGaAs/GaAs well structures

“…The InAs QD PL intensity quenching is usually attributed to thermal escape of carriers from the QDs to the wetting layer (WL) or to the GaAs barrier with following recombination via non-radiative (NR) centers [4,5]. In DWELL structures the introduction of surrounding QWs changes the height of potential barriers for exciton thermal escape from QDs and can increase the density of NR centers.…”

InAs Quantum Dots in Symmetric InGaAs/GaAs Quantum Wells

“…It is clear from the formula (6), that in high quality QD structures (#2, #3 and #4) with low concentrations of the NR1 and NR2 centres the PL intensity I(T) is linearly dependent on excitation power (or generation rates, G InGaAs , G GaAs ), as it is demonstrated in Fig.5. In low quality QD structures (#1 and #5) photo-generated excitons recombine partially via NR1 and NR2 centres and W (T) changes Sublineary versus power (Fig.5).…”

“…PL intensity decay in InAs QDs as a rule attributed to thermal escape of carriers from QDs into the wetting layer or into the GaAs barrier [5][6][7][8], as well as to thermally activated capture of excitons by nonradiative defects in the GaAs barrier or at the GaAs/InAs interface [5,9,10]. The unusual variations of emission energy and the full width at half maximum (FWHM) of PL bands in the InAs/GaAs self-assembled QDs have been investigated earlier as well [11,12].…”

“…In these systems, the strong localization of an electronic wave function leads to an atomic-like electronic density of states and permits to realize the novel and improved photonic and electronic devices. Microlectronic and optoelectronic devices based on quantum wells (QWs) with InAs QDs have been the subject of investigation for the applications in semiconductor lasers for the optical fiber communication [1][2][3], infrared photo-detectors [4][5][6], electronic memory devices [7,8], as well as single electron devices and single photon light sources on the base of single-QD structures for the quantum information applications [9][10][11][12]. QDs are especially attractive for the applications in semiconductor lasers.…”

A novel approach to increase emission wavelength of InAs/GaAs quantum dots by using a quaternary capping layer

“…The size and hence emis− sion wavelength can be tuned by changing the growth con− ditions [7]. It has been shown that an increase in the InAs monolayer coverage leads to larger dots [8]. But increasing the monolayer coverage beyond 3 ML leads to other prob− lems such as coalescing of islands causing large non−unifor− mities in dot size [9].…”