Room Temperature Carrier Kinetics in the W-type GaInAsSb/InAs/AlSb Quantum Well Structure Emitting in Mid-Infrared Spectral Range

Abstract

Room temperature carrier kinetics has been investigated in the type-II W-design AlSb/InAs/ Ga0.80In0.20As0.15Sb0.85/InAs/AlSb quantum well emitting in the mid-infrared spectral range (at 2.54 µm). A timeresolved reflectance technique, employing the non-degenerated pump-probe scheme, has been used as a main experimental tool. Based on that, a primary carrier relaxation time of 2.3 ± 0.2 ps has been found, and attributed to the initial carrier cooling process within the quantum well states, while going towards the ground state via the carrier-optical phonon scattering mechanism. The decay of a quasi-equilibrium carrier population at the quantum well ground states is primarily governed by two relaxation channels: (i) radiative recombination within distribution of spatially separated electrons and holes that occurs in the nanosecond time scale, and (ii) the hole tunnelling out of its confining potential, characterized by a 240 ± 10 ps time constant.

Ultrafast infrared spectroscopy of InAs/GaSb and InAs/InAsSb type-II superlattices

“…Since pump laser energy is higher than the energy of e1hh1 transition, generated carriers need to thermalize through electron-electron scattering process to the bottom of the band which is usually realized in a matter of femtoseconds. Rapid decay of the signal from the maximum TA indicates the depopulation of the excited states through some other process than radiative recombination characterized often by nanosecond timescale 37 . There are several possible interpretations of this process [38][39][40] , for example, hot carriers tunneling through the barrier out of the quantum confinement 37 or recombination through defect centers that have been shown here to be present in both types of structures.…”

“…Rapid decay of the signal from the maximum TA indicates the depopulation of the excited states through some other process than radiative recombination characterized often by nanosecond timescale 37 . There are several possible interpretations of this process [38][39][40] , for example, hot carriers tunneling through the barrier out of the quantum confinement 37 or recombination through defect centers that have been shown here to be present in both types of structures.…”

Carrier dynamics of type-II InAsSb/GaAsSb W-quantum wells emitting in mid-infrared

“…The shorter one could be explained by the non-radiative recombination in the structure or hole tunnelling from the quantum well through the barrier. 17 The longer time scale is connected to the recombination time in the energy of fundamental transition. This nanosecond-long value is increased from 840ps for 2s soak time sample to 5100 ps in the 6s soak time one.…”

Carrier Dynamics in Thin Germanium–Tin Epilayers

“…The experiment is set up in the reflection mode. A Ti:sapphire ultrafast oscillator was used as an excitation source. , The oscillator generates trains of ∼140 fs-long pump pulses at a repetition frequency of 76 MHz with the E pump = 1.49 eV photon energy in the pulse. The pulse train synchronously feeds the optical parametric oscillator, in which the nonlinear photon energy conversion allowed for the tuning of the probe pulse photon energy in the range of ∼0.54 to ∼0.67 eV.…”