Emission characteristics of InGaAs/GaAs quantum dot microtube ring resonators

In this paper, we have performed a detailed investigation of the cathodoluminescence characteristics of InGaAs/GaAs QD microtube ring resonators fabricated by a single-step lithography process. We have unambiguously demonstrated that self-organized QD layers embedded in rolled-up microtube structures can exhibit significantly improved luminescence efficiency, compared to the as-grown layers. In addition, we have observed, for the first time, optical modes in rolled-up microtubes with an average wall thickness of 75 nm that is significantly smaller than the light wavelength (~ 1.0 mum). The results agree well with detailed analysis using finite-difference time-domain methods.