Nanoscale coherent light sources on GaAs and Si using single rolled-up InGaAs/GaAs quantum dot microtubes

In this report we study the nanoscale coherent light sources on GaAs and Si using single rolled-up InGaAs/GaAs quantum dot microtubes. Such microtubes are formed by self-rolling of coherently strained InGaAs/GaAs quantum dot heterostructures through controlled release from their host substrates [1-3]. We have developed a substrate-on-substrate transfer process [3] and realized nearly defect-free quantum dot microtubes on Si that were not possible before. Emission characteristics of InGaAs/GaAs quantum microtubes were studied using micro-photoluminescence spectroscopy at 300 K. A typical emission spectrum measured from the freestanding region of a microtube without any intentional surface corrugations (inset) is shown in Fig. 3(a) (solid line), which is characterized by a sequence of regularly spaced optical resonance modes superimposed on a broad quantum dot emission spectrum (dotted line). These resonance modes arise from photons circulated around the periphery of the microtube by total internal reflections.