Search

We report on the optical characterisation of single indium phosphide (InP) semiconductor nanowires trapped in a gradient force optical tweezers. Nanowires studies were of zinc blende, wurtzite or mixed phase crystal poly-types and ranged in length from 1

In this letter, we demonstrate that microphotoluminescence may be combined with optical trapping for effective optical characterization of single target InP semiconductor nanowires in suspension. Using this technique, we may investigate structural properties of optically trapped nanowires, such as crystalline polytypes and stacking faults. This arrangement may also be used to resolve structural variations along the axis of the trapped nanowire. These results show that photoluminescence measurements may be coupled with optical tweezers without degrading the performance of the optical trap and provide a powerful interrogation tool for preselection of components for nanowire photonic devices.

The interdiffusion rate of group-V and group-III sublattice atoms in InxGa1-xAs/InP quantum well structures induced by proton implantation has been investigated using differential reflectance (DR), photoluminescence (PL) and theoretical modelling. Based on DR, PL and modelling results, we found the unique value of k (LV/LIII) ratio for three different InGaAs quantum well structures, namely lattice matched (LM), tensile strained (TS) and compressively strained (CS). The k ratio of TS, LM and CS was 1.05, 1.25 and 1.40 respectively. These ratios were slightly higher than unity indicating that the diffusion coefficient of the group-V sublattice was larger than that of the diffusion coefficient of the group-III sublattice. Change in the interdiffusion rate of group V and group III in the lattice-matched and strained (TS, CS) quantum well structures was most likely due to the different strain profile developed in the quantum well region as a result of changing the quantum well composition.

Two of the most important intermixing techniques, ion implantation and impurity free vacancy disordering, are investigated and compared in InGaAs/(Al)GaAs quantum well (QW) and quantum dot (QD) structures. For ion implantation induced intermixing, arsenic implantation was performed and the amount of interdiffusion created was found to vary as a function of implantation dose and temperature. Impurity free vacancy disordering was also enhanced by deposition of SiO2 in both QW and QD structures and annealing at different temperatures. In order to obtain large differential energy shifts for device integration using both methods, the essential issue of suppression of thermal interdiffusion using a TiO2 capping layer was also addressed.

In this article, we investigate the parameters used in the MOCVD growth of GaAsN epilayers on GaAs substrates and some of their microstructures and optical properties. The N incorporation was found to mainly depend on the growth temperature and the fractional 1,1-dimethylhydrazine molar flow. A thin highly strained interface layer was observed between GaAsN and GaAs, which, contrary to previously published results, was not N enriched. The low-temperature (10K) photoluminescence spectra were composed of several emissions that we attribute to a combination of interband transition and transitions involving localized defect states.

We have used ion implantation for erbium doping of mesoporous silicon microcavities. Optically active erbium-doped microcavities with Q factors in excess of 1500 have been demonstrated. We observed strong modification of the emission properties of the erbium in the microcavity with an accompanying cavity enhancement factor of 25. In addition, power- and temperature-dependent photoluminescence measurements indicate that erbium-implanted porous silicon has excitation mechanism very similar to that of erbium in a crystalline silicon host.

The ion implanted semi-insulating InP was analyzed at increased annealing temperature for its structural, electrical and optical properties. The damage from the implantations was predicted using transport of ions in matter (TRIM) simulations. To obtain the electrical characterstics, scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) were used.The density of defects after the implantations was confirmed by X-ray and transmission electron microscopy (TEM). Analysis show that the amount and type of damage caused by implantation did not scale with implant ion atomic mass.