Jan 30, 2013
Nanowires and belts show inhomogeneity in optical phases
Using a variety of techniques, researchers have studied single nanostructures to determine the intrinsic responses of doped nanowires or belts to elementary excitations. After careful examination of the local luminescence or Raman signals, the samples were seen to possess rich microscopic electronic or optical phases. These phases often cannot be discriminated by XRD techniques.
If the optical phase is large enough, the structures produce several optical domains and even coupled optical cavities. Luminescence mapping of individual ZnSe:Mn nanowires show that different emission lines, different modes occur only at some positions of the wire. Also, this kind of structure displays different luminescence behaviours and spectral distribution under CW and nanosecond pulse laser excitation.
The wires and belts also exhibit different behaviours representative of multi-QDs and multi-QWs, respectively, to show different optical or electronic coherence in the confined space, and confine spatially some of the excitations.
This kind of microstructure may be considered to be a natural superlattice structure by simple growth, much cheaper than the current MBE technique, and with sharper boundaries.
These micro-nanostructures may find applications in new light sources, nonlinear optical devices, waveguides, and for studying quantum electrodynamics in microcavities, interactions between excitons and other excitations, excitonic BECs and quantum entanglement.
A full description of the work can be found in the journal Nanotechnology.
About the author
The study was conducted by researchers from the micro-nano technology center, Beijing Institute of Technology (BIT) in Beijing and the Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of the Ministry of Education, College of Physics and Information Science, Hunan Normal University (HNNU) in Changsha. Some staff from the School of Physics and Microelectronics Science at Hunan University (HNU) in Changsha also helped in some experiments. The teams are part of a collaborative research unit funded by the Changjiang scholarship of China. Weichang Zhou is a teacher at the College of Physics and Information Science, Hunan Normal University, he synthesized the samples and obtained the Raman and PL spectra. Dr Ruibin Liu is an associate professor of BIT, he completed the lasing experiment and analysed the results. Dongsheng Tang is the professor of HNNU, he helped a lot to characterize the belt and wire structure and composition. Anlian Pan is a professor at HNU and previous member of Prof. Zou’s team. He advised on sample synthesis. Xiaoxu Wang is a PhD graduate student, she helped to finish the Raman mapping of some samples. Dr QInglin Zhang helped Weichang to complete the PL mapping, Dr Qiang Wan helped to finish some characterization of the sample with PL and SEM. Dr Haiming Fan had fruitful discussion with Prof. Zou about the exciton interactions at high density and Raman responses of a single wire, and gave advice on the description of related results. Prof. Zou is group leader and head of the micro-nano center at BIT. He has strong interests in nanophotonic materials, physics and devices.