Research Of The Key Technology For Nanolaser

Ultraviolet semiconductor lasers are widely used for applications in photonics, information storage, biology and medical therapeutics. Although the performance of gallium nitride ultraviolet lasers has improved significantly over the past decade, demand for lower costs, higher powers and shorter wavelengths has motivated interest in zinc oxide(ZnO), which has a wide direct bandgap and a large exciton binding energy. ZnO-based random lasing has been demonstrated with both optical and electrical pumping.The main contents of this paper include two parts:Firstly, this paper have proposed a novel surface plasmonic nanolaser based on a nanowires/air gap/metal thin film hybrid structure by using theoretical research and simulated analysis. An air groove was opened in the MgF2 insulating layer, than making the nanowire embedded on the top of the air slot, but maintaining a gap between the nanowire and the metal layer, thereby resulting in a coupled hybrid plasmonic waveguide and a significant field enhancement effect. This structure enables the realization of an air gap. By simulating the modal properties and the lasing threshold of the hybrid plasmonic mode under different geometric parameters, it is demonstrated that capable of subwavelength con?nement with low propagation loss and high field con?nement. Ultimately we achieve the nanolaser’s optimal structure size.Compared with the general diffraction limited lasers, this structure can reduce the physical size of the device and the physical mode. The proposed nanolasers could be easily integrated with various nanophotonic devices, and has the potency as an appealing candidate for future active plasmonic systems.Secondly, ZnO photodiodes consisted of high quality N-doped ZnO nanowires grown on n-GaN layer covered c-plane sapphire wafers were studied in this paper. The Au catalyzed ZnO nanowires were grown by chemical vapor deposition with excellent wurtzite structure. The p-ZnO/n-GaN heterojunction can be successfully formed on c-plane sapphire substrates by CVD. Structural and optical characteristics, electrical characteristics were measured by XRD, micro-Raman, PL and I-V measurements, respectively, to demonstrate the p-n heterojunction compared with the n-ZnO/GaN sample. I-V characteristics of the photodiodes show a rectifying diode behavior. Moreover, the pure ZnO/n-GaN sample was compared and analyzed to verify that the p-type conductivity of heterojunction devices. We confirmed that such p-ZnO/n-GaN heterojunction devices exhibit distinct light emission when the electrode is applied with forward bias voltage. The lasing behavior of the p-n junction is showed a threshold of 406 mW/cm2 by using optical pumping. Most of the samples could be observed distinct light emission in 20 or 30 mA pumping current. For the n-ZnO/GaN device, reverse the direction of the applied voltage, some weak yellow light could be observed. This study not only proved the successful preparation of p-type ZnO nanowires by nitrogen doping, but also the ultraviolet heterojunction photodiods based on p-type ZnO nanowires grown on GaN film. The realization of p-type ZnO nanowire arrays with durable and controlled transport properties is important for the fabrication of nanoscale electronic and optoelectronic devices.