Semiconductor Photonics: Nano-Structured Materials and Devices

Paper Title Page

Authors: Xiao Song Zhang, Lan Li, Dong Qing Dong, Zhi Wang, Xiao Yi Dong
Abstract: ZnS:Mn quantum dots were prepared in the aqueous medium from readily available precursors. The construction, morphology and luminescence properties of the ZnS:Mn quantum dots were evaluated by XRD,TEM and photoluminescence spectra. The blue and orange emission of the ZnS:Mn quantum dots excited by a 532nm picosecond laser were discussed.
Authors: Jing Mei Lu, Xuan Cheng
Abstract: The porous silicon (PS) layers were fabricated on n(100) and n(111) silicon by applying the constant and repeated currents in different HF solutions. The electrochemical impedance spectroscopy (EIS) was used to in-situ characterize the Si/electrolyte interface before and after the PS formations. The surface and structure of PS layers were examined in terms of electrochemical/surface parameters.
Authors: Boon S. Ooi, Hery S. Djie, Amr.S. Helmy, James C.M. Hwang
Abstract: We report on the development of wide gain InAs/InGaAlAs/InP quantum-dash structure for broadband diode laser and amplifier. Characterizations of this material system have been performed using spectroscopy and microscopy techniques. Gain-guided broad area laser fabricated using this material system exhibits lasing wavelength coverage of up to 76 nm at ~1.64 (m center wavelength from simultaneous multiple confined states lasing at room temperature.
Authors: Hyeon Seok Lee, Heon Yong Lee, S.Y. Ahn, K.H. Kim, J.Y. Kwon
Abstract: We fabricated improved carbon counter electrodes to improve conversion efficiency of dye sensitized solar cells (DSSCs). Unlike conventional carbon counter electrodes, we added small quantity of TiO2 nano powder and used chemical sintering methodology developed by Park’s group to make surface morphology of the electrodes to change. Through these methods, we could observe change of surface morphology of carbon electrodes and influences on short circuit current density (JSC) and conversion efficiency.
Authors: Y.H. Ding, V. Hongpinyo, Hery S. Djie, Boon S. Ooi
Abstract: Nano-scale spatial wavelength engineering of quantum nanostructures using nitrogen ion-implantation induced intermixing has been developed for tuning the bandgap of quantum-well, quantum-dash-in-well, and quantum-dot nanostructures. High performance bandgap-tuned quantum-well and quantum-dash lasers fabricated using this technique has been demonstrated.
Authors: A.A.D.T. Adikaari, N.K. Mudugamuwa, S.R.P. Silva
Abstract: Excimer lasers have been utilized for the crystallization of hydrogenated amorphous silicon for electronic applications. These lasers typically operate in the ultraviolet and hence photons are absorbed by the silicon thin films within a few nanometres of the surface, melting and solidifying the silicon on a nanosecond timescale, often without affecting the underlying substrate. This technique enables the use of inexpensive substrates, such as glass, which are highly preferable for low cost, large-area electronic devices. The depth of crystallization becomes important for applications such as photovoltaics, which depends on a number of factors; with laser beam shape one of the most significant. A Gaussian beam profile has been reported to be best suited for controlled evolution of hydrogen during crystallization with minimum surface damage. Previous reports show the typical energy densities of crystallization, comparing the crystalline volume and surface roughness of the resultant films for different film thicknesses. We report significant reductions of laser energy densities for crystallization by modifying the Gaussian pulse profile, while retaining the controlled evolution of hydrogen from hydrogenated amorphous silicon films. An asymmetrical, shorter pulse profile retains the desirable gradual leading edge of the Gaussian pulse for controlled evaporation of hydrogen, while increasing the peak energy. The resultant films show increased surface roughness along with higher crystalline volumes, which may be beneficial for photovoltaics.
Authors: Jing Hua Teng, Lip Fah Chong, J.R. Dong, Soo Jin Chua, Norman Soo Seng Ang, Yan Jun Wang, Ee Leong Lim
Abstract: In this paper, we report a DFB laser diode with a buried SiO2 grating. Epitaxy lateral overgrowth by metalorganic chemical vapour deposition (MOCVD) is conducted to grow the p-type InP cladding layers in the nano-patterned dielectric grating template. The large refractive index difference between SiO2 and InP results an index coupling coefficient κ of about 250 cm-1. The fabricated DFB laser showed a side mode suppression ratio larger than 45 dB measured. The technology developed can also be used for other applications that require high efficiency grating structure.
Authors: Hong Quang Le, Soo Jin Chua
Abstract: Single ZnO nanorods with diameters of 100nm were directly grown on GaN surface by using low-temperature hydrothermal synthesis. Individual nanorods were removed from the substrate and placed between the Au contact pads and the current voltage measurement was proceeded to characterize the electrical properties of the ZnO nanorods. By using thermionic field emission model of Padovani and Stratton , the resistivity, carrier concentration, electron mobility can be extracted with the values of 0.14 Ωcm, 9.2x1016/cm3,33.82cm2V-1s-1, respectively. The single ZnO nanorods also showed high sensitivity to the UV light (325nm). Under the UV illumination, the UV induced current increase nearly 10 times than the dark current. In addition, the nanorods also exhibited a slow UV response due to the effects of the oxygen ions on the surface of the nanorods.
Authors: Olga A. Shalygina, Denis M. Zhigunov, Dmitrii A. Palenov, Victor Timoshenko, Pavel K. Kashkarov, M. Zacharias, Paul M. Koenraad
Abstract: We report on the experimental and theoretical studies of population/depopulation dynamics of excitons in the structures with Si nanocrystals in SiO2 matrix (nc-Si/SiO2) under strong optical excitation. The experimental results are explained using a phenomenological model based on rate equations for coupled system of energy donors (excitons) and energy acceptors (erbium ions). Exciton luminescence is found to exhibit superlinear dependence for Er-doped samples. At the same time the Er-related luminescence at 1.5 μm shows a saturation of the intensity and shortening of the lifetime, which are attributed to the population inversion of the Er ions states. The obtained results demonstrate that nc-Si/SiO2:Er systems can be used for applications in Si-based optical amplifiers and lasers, compatible with planar Si-technology.

Showing 51 to 60 of 75 Paper Titles