Excitonic properties and near-infrared coherent random lasing in vertically aligned CdSe nanowires.

One-dimensional (1D) semiconductor nanowires (NWs) have drawn considerable research attention over the past few decades because of their unique properties and potential applications in nanoelectronics, photonics, luminescent materials, lasing materials, and biological and medical sensing. [ 1–3 ] Impressive progress has been demonstrated in highly effi cient light sources (nanolasers), waveguides, fi eld-effect transistors and photodetectors based on group IV elements (Si and Ge), [ 4 ] III–V compound semiconductors (GaN and GaAs), [ 2 , 5 ] and semiconducting oxides (ZnO, SnO 2 and In 2 O 3 ). [ 6 , 7 ] Owing to its direct bandgap (ca. 1.74 eV at room temperature), good absorption ability, and excellent photosensitivity, [ 8 , 9 ] CdSe is recognized as a promising light-harvesting material to be applied in optoelectronics. Especially, the fundamental emission of CdSe falls in the near-infrared (NIR) region, and biosensors operating in this region can avoid interference from biological media such as tissue autofl uorescence and scattering light, and thereby facilitate relatively interference-free sensing. [ 10 ]