Approaching transform-limited photons from nanowire quantum dots using excitation above the band gap

We demonstrate that, even when employing above-band excitation, photons emitted from semiconductor quantum dots can have linewidths that approach their transform-limited values. This is accomplished by using embedded in bottom-up photonic nanowires, an which mitigates several potential mechanisms result linewidth broadening: (i) only a single dot present each device, (ii) nucleation proceeds without the formation of wetting layer, and (iii) sidewalls nanowire are comprised not etched facets, but epitaxially grown crystal planes. Using these structures we achieve 2x transform limit, unprecedented for excitation. also highly nonlinear dependence on both excitation power temperature be described independent Boson model considers deformation piezoelectric exciton-phonon coupling. find sufficiently low powers temperatures, observed excess broadening dominated phonon dephasing, surprising considering high occupation occurs with