Effect of carrier transfer on the PL intensity in self-assembled In (Ga) As/GaAs quantum rings

Abstract

Abstract. We present results concerning the carrier transfer between In(Ga)As quantum rings in a stacked multilayer structure, which is characterised by a bimodal size distribution. This transfer of carriers explains the observed temperature behaviour of diode lasers based on that kind of stacked layer structures. The inter-ring carrier transfer can be possible by phonon assisted tunnelling from the ground state of the smallring family towards the big-ring family of the bimodal size distribution. This process is thermally activated in the range 40-80 K. PACS

Size dependent carrier thermal escape and transfer in bimodally distributed self assembled InAs/GaAs quantum dots

“…In both samples, above a certain temperature the decay time falls to a sub-nanosecond scale due to the activation of non-radiative channels. 4,13,37,[39][40][41] The observed temperatures at which PL decay times begin to decrease in Figure 5 are in good correspondence with the QD Arrhenius plots. As observed for the integrated intensity, the PL decay time increases in the low temperature range.…”

“…This PL-temperature trend is an accepted signature of a carrier thermal transfer. 7,13,22,[35][36][37][38] However, there are some particularities which must be taken into account. The integrated intensity from sample I SQD band increases at intermediate temperatures.…”

The effect of high-In content capping layers on low-density bimodal-sized InAs quantum dots

“…This behavior has been already observed in similar structures and it has been justified by different hypotheses including resonant energy levels between different families, 40 losses of carriers from the WL to the GaAs, 26,36 losses within the barrier itself, 38,39 or losses related to defects. 8,11,37 With the exception of the structure with x ¼ 0.30, three regions can be distinguished in the temperature variation of the recombination time in all samples for QD1 (Fig.…”

Thermal activated carrier transfer between InAs quantum dots in very low density samples

“…During the last decade, a great effort has been made studying the temperature evolution of QD emission, obtaining good agreements between experimental data and kinetic exciton recombination models [4]. Thermal escape through the wetting layer (WL) or by phonon assisted tunneling is usually claimed as the most suitable mechanism to describe carrier transfer between QDs both in monomodal and bimodal distributions [5][6][7].…”

“…During the last decade, a great effort has been made studying the temperature evolution of QD emission, obtaining good agreements between experimental data and kinetic exciton recombination models [4]. Thermal escape through the wetting layer (WL) or by phonon assisted tunneling is usually claimed as the most suitable mechanism to describe carrier transfer between QDs both in monomodal and bimodal distributions [5][6][7].In the present study we have analyzed this phenomenon in two different samples containing very low density of InAs/GaAs QDs. This is important because we can separate the μPL spectra from different QDs within the illumination area and hence compare more directly microscopic and ensemble exciton recombination dynamics.…”