Photoluminescence of double quantum wells: asymmetry and excitation laser wavelength effects

C. A. Bravo-Velazquez; L. F Lastras-Martinez; O. Ruiz-Cigarrillo; G. Flores-Rangel; L. E Tapia-Rodriguez; K. Biermann; P. V. Santos

doi:10.1002/pssb.202100612

arXiv · 2201.10690

Photoluminescence of double quantum wells: asymmetry and excitation laser wavelength effects

C. A. Bravo-Velazquez·L. F Lastras-Martinez·O. Ruiz-Cigarrillo·G. Flores-Rangel·L. E Tapia-Rodriguez·K. Biermann·P. V. Santos

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Abstract

Circularly polarized photoluminescence (PL) spectroscopy measured at 19 K on GaAs/AlGaAs symmetric and asymmetric double quantum wells (DQW) is reported. The PL is obtained by exciting the sample with a circularly polarized (left or right) laser in order to create an initial unbalanced distribution of electron spins in the conduction band and, in this way, obtain the electron spin lifetime $\tau_s$. The effects of the excitation laser wavelength were estimated by exciting with laser wavelengths of 701.0 nm, 787.0 nm, 801.5 nm and 806.5 nm. The increase of $\tau_s$ with the excitation wavelength is attributed to the lower initial quasi-momentum $\bf{k}$ of the excited carriers, which also reduces spin-orbit relaxation processes. $\tau_s$ was found to be higher in asymmetric DQWs: this is attributed to the wider QWs in these samples, which reduces spin relaxation due to the Dresselhaus mechanism. In addition, we also detected a smaller contribution from the Rashba mechanism by comparing samples with built-in electric fields of different orientations defined by doped barrier layers.

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C. A. Bravo-Velazquez, L. F Lastras-Martinez, O. Ruiz-Cigarrillo, G. Flores-Rangel, L. E Tapia-Rodriguez, K. Biermann, P. V. Santos. 2022-01-26. Photoluminescence of double quantum wells: asymmetry and excitation laser wavelength effects. https://doi.org/10.1002/pssb.202100612

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