Short exciton radiative lifetime in submonolayer InGaAs∕GaAs quantum dots

Abstract

The exciton radiative lifetime in submonolayer (SML) InGaAs∕GaAs quantum dots (QDs) grown at 500°C was measured by using time-resolved photoluminescence from 10to260K. The radiative lifetime is around 90ps and is independent of temperature below 50K. The observed short radiative lifetime is a key reason for the high performance of SML QD devices and can be explained by the theory of Andreani et al. [Phys. Rev. B 60, 13276 (1999)] calculating the radiative lifetime of QDs formed at the interface fluctuations of a quantum well, as the SML QDs are 20–30nm in diameter and embedded within the lateral InGaAs QW.

Long luminescence lifetime in self-assembled InGaAs/GaAs quantum dots at room temperature

“…1 The radiative lifetime of the excitons in QDs at room temperature is one of the most important device parameters, being inversely proportional to the modal gain of QD lasers. [2][3][4][5] The radiative lifetime of strongly confined excitons in QDs, where the energy separation between the ground state and the first excited exciton state is larger than the thermal energy k B T ͑k B is the Boltzmann constant and T is the temperature͒, should be almost independent of T. However, in real QDs, the radiative lifetime of the ground state excitons is expected to increase with increasing temperature due to the thermal population of optically inactive or poorly active exciton states. [6][7][8] This phenomenon was first observed in InGaAs/GaAs QDs by Wang et al 9 in 1994, in InAs/GaAs QDs by Yu et al 10 in 1996, and by other groups later.…”

Fast gain and phase recovery of semiconductor optical amplifiers based on submonolayer quantum dots

“…31,32 The value of 800 ps for s 1cPP 2 in the absorption regime agrees well with the radiative lifetime reported for SML excitons. 33,34 The dynamics observed for the phase recovery is similar to the gain recovery, except for the amplitude distribution between fast and slow components (Fig. 3(b)).…”

Abnormal photoluminescence properties of InAs/InAsSb in-plane ultrahigh-density quantum dots

“…26) The non-radiative lifetime subsequently decreased with increasing temperature due to the thermal escape of QDs, from around 120-250 K. The PL decay lifetime plots of LD QDs exhibited a response similar to that found in several studies. 27,28) Conversely, the GSs of UHD QDs maintained their lifetimes until 50 K. This nearly constant PL lifetime indicated weak carrier delocalization in small QDs. Since the majority of carriers originated from the GSs, strong coupling was not observed before 100 K, as indicated in Fig.…”