Abstract
Optical properties of free-standing GaAs/AlGaAs single quantum well (SQW) microtubes have been investigated by room-temperature micro-photoluminescence (PL) and Raman measurements, followed by the detailed comparison with the corresponding properties of InGaAs/GaAs bilayer microtubes. Single peaks originating from GaAs SQW (~824nm) and bulk GaAs (~870nm) were observed in PL spectra of free-standing SQW and bilayer microtubes, respectively, which clearly shows the quantum-confinement-effect (QCE)-induced blue shift (~46nm) of GaAs PL peaks. The spectral red-shift (~12nm) of SQW PL peak due to strain release was confirmed after the as-grown planar rolled up into microtube. For Raman spectra, both GaAs-like and AlAs-like LO phonons of Al0.3Ga0.7As barrier which demonstrated the two-mode behavior were observed for SQW microtubes. Meanwhile, all LO phonon modes of SQW microtube were obviously red-shifted to lower frequencies (~10cm−1) when compared with SQW planar, reflecting the compressive strain decreases.
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