Room temperature observation of optical modes in transferred rolled-up InGaAs/GaAs quantum dot microtube with AlGaAs confining layers

We realized the excellent confinement of carriers in single-layer InAs quantum dots (QDs) via introducing two AlGaAs confining layers (CLs), and then fabricated the corresponding rolled-up InGaAs/GaAs QD microtubes by conventional photolithography and wet-etching. Subsequently, the as-fabricated AlGaAs confined QD microtubes were transferred to a Si-based SiOx substrate using a simple liquid-assisted substrate-on-substrate transfer process, thus obtaining the microtube ring resonators. Through micro-photoluminescence (µPL) measurement, optical modes were observed at room temperature and a maximum Q-factor of ~ 550 was demonstrated. In order to clearly show the effect of AlGaAs CLs, we also fabricated and transferred QD microtubes without AlGaAs CLs for comparison. µPL spectra collected at 80 K confirmed that the PL intensity of the central optical mode was increased ~ 10 times with the assistance of AlGaAs CLs. We have confidence that QD microtube ring resonators can be further improved through the incorporation of double-layer QDs together with AlGaAs CLs.