Photoluminescence dynamics in GaAs/AlGaAs quantum wells under pulsed intersubband excitation

Abstract

We investigate the time-resolved photoluminescence (PL) dynamics of an undoped GaAs/AlGaAs multiple quantum well under mid-infrared (MIR) irradiation. A time-delayed MIR laser pulse from a free-electron laser, tuned to the intersubband transition energy of the quantum well, induces temporal quenching of the PL intensity with subsequent recovery. The experimental data can be accurately described by a simple rate-equation model, which accounts for the cooling of the non-radiative states to radiative states. By performing polarization sensitive measurements, we are able to discriminate the contributions of free-carrier absorption from that of intersubband absorption, where the latter is about 50 times more efficient

In-plane interdot carrier transfer in InAs/GaAs quantum dots

“…For the QW sample in Ref. 15, the PL rise and recovery times were found to be practically identical. However, this does not hold for QD ensembles as the mechanism of relaxation of the carriers is different.…”

“…Such interdot carrier transfer in these samples has been reported earlier 9 leading to trapped-carrier luminescence. For comparison, in quantum well (QW) samples 15 where PL is emitted from only one energy level, the amount of recovery balances the number of quenched carriers for the given transition. For a quantitative understanding we fitted our data with a multi-level rate equation model, which has been used for PL quenching in QWs.…”

“…For a quantitative understanding we fitted our data with a multi-level rate equation model, which has been used for PL quenching in QWs. 15 Here we will discuss some of the basic features and modifications of the model. The PL intensity was proportional to the occupation number of the radiative state.…”

Concentration-size dependences for the electron energy in Alx Ga1-xAs/GaAs/AlxGa1-xAs nanofilms

“…Up to date, there are rather many semiconductor compounds suitable for creation of a new electron, optoelectronic, quantum-optic, and other devices based on the well-known heterojunction Al x Ga 1-x As/GaAs [5][6][7][8] and in-depth studying the low-dimensional nano-systems on its base [9][10][11]. In particular, they ascertained the opportunity to tune the energy spectrum of 2D electrons in quantum wells (QW) GaAs with Al x Ga 1-x As barrier layers.…”

Characterizing intra-exciton Coulomb scattering in terahertz excitations

“…Figure 1(a) shows that at the arrival time of the THz pulse, defined as time zero, the 1s PL is quenched as the 1s population is transferred by the absorbed THz photons into higher-energy states, in agreement with earlier experiments. [16][17][18] Additionally, the THz pulse generates excess 2s PL, identifying a genuine many-body signature. As explained in Ref.…”