Luminescence investigations of the GaP-based dilute nitride Ga(NAsP) material system

Multi-quantum well heterostructures (MQWHs) of the novel Ga(NAsP)/GaP material system have been grown, pseudomorphically strained to GaP-substrate. The crystalline perfection is verified by transmission electron microscopy (TEM). For As-concentrations in excess of about 70%, a direct band structure and adequate luminescence efficiency for laser device application is observed. Temperature-dependent photoluminescence (PL) investigations show the influence of carrier localisation and non-radiative recombination processes typical for dilute nitride materials. With rising N content in the active material, the emission wavelength shifts towards longer wavelength, leading to Ga(NAs)/GaP MQW structures with photon energies below the indirect band gap of silicon (Si). At the same time the luminescence intensity drops due to an increase in non-radiative carrier traps and/or structural degradation.     

Three terminals optoelectronics devices integrated into a silicon on silicon waveguide

In this paper we describe two different kind of optoelectronic devices both based on a three terminals active device and exploit the plasma dispersion effect to achieve the desired working. The first device exploits this effect in order to obtain an optical modulation. The second device is an optoelectronic router based on the mode-mixing principle together with the injection-induced optical phase shift. Both devices are integrated into a Silicon on Silicon optical channel waveguide which can be realized using a standard bipolar process. The possibility of using standard, well-known technology presents several advantages with respect to III–V Optoelectronics. The active three terminal device used is a Bipolar Mode Field Effect Transistor (BMFET). Numerical simulation results are presented on both devices.     

超快光电测量技术

本文综述了近年来趔快光电测量技术的新进展，其中包括扭快光电材料的特性、高速光电器件的基本原理，着重介绍了若干主要的用快光电测量技术．     

π-CONJUGATED OLIGOMERS IN SUPRAMOLECULAR CRYSTALS AND THEIR OPTOELECTRONIC FUNCTIONS

Functional organic molecular materials and conjugated oligomers or polymers now allow the low-cost fabrication of thin films for insertion into new generations of electronic and optoelectronic devices. The performance of these devices relies on the understanding and optimization of several complementary processes. Our goal is to discuss the relationship between the molecular stacking structures and their optoelectronic properties that are of importance in all these areas. The concept of intermolecular interaction should be taken here in the special sense that is inter-dipole coupling. Specifically, we will address the impact of inter-dipole interaction between adjacent molecules in aggregate state on the solid-state emission properties.     

Design and Performances of a Carbon Monoxide Sensor Using Mid-Infrared Absorption Spectroscopy Technique at 4.6 µm

Based on infrared absorption spectroscopy technique, a carbon monoxide sensor was developed using the fundamental absorption band of carbon monoxide molecule at the wavelength around 4.6 µm. The developed sensor consists of pulse-modulated wideband incandescence, open ellipsoid light-collector gas-cell, dual-channel detector, and control and signal-processing module. With the prepared standard carbon monoxide gas sample, sensing characteristics on carbon monoxide were investigated using the sensor. Experimental results reveal that the limit of detection is about 10 ppm, the relative error at the limit of detection point is less than 14%, and that is less than 7.8% within the low concentration range of 20～180 ppm. The maximum absolute errors of 50 min long-term measurement on the 0 and 14 ppm CO gas samples are about 3 and 3.17 ppm, respectively, and the standard deviations are as small as 0.18 and 1.25 ppm, respectively. Compared with the reported carbon monoxide detection systems utilizing quantum cascaded lasers and distributed feedback lasers, the proposed sensor shows potential applications in carbon monoxide detection under the circumstances of coal-mine and environmental protection, by virtue of high performance, low cost, simple optical structure, and so on.     

二维半导体材料与器件——从传统二维光电材料到石墨炔

近年来,二维半导体材料由于其独特的材料结构和电子输运特性得到了科学界的广泛关注,被应用于光电器件、催化和生物传感器等领域。本文系统概述了传统二维材料以及新兴二维材料石墨炔的发现和发展历程。重点聚焦在二维材料在光探测器领域中的应用,探讨了不同二维材料体系及器件结构对光探测器性能的影响;并详细介绍了新兴二维材料——石墨炔,及其合成和应用。展望了传统二维材料及石墨炔在光电转换器件的应用中所面临的机遇和挑战。     

Theoretical Study on the Structural and Optoelectronic Properties of the Linear Perfluorooctane Sulfonate （PFOS）

The perfluoroalkyl substances(PFS) have attracted considerable attention in recent years as a persistent global pollutant to be able to bioaccumulate in higher organisms.In this paper,theoretical analysis on electronic structures,optoelectronic properties and absorption spectra properties of the perflurooctane sulfonate(PFOS) in gas phase have been investigated by using the DFT/TD-DFT method.The geometric structures,electrostatic potentials,energy gaps,ionization potentials,electron affinities,frontier molecular orbital,excitation energies and absorption spectra for the ground state of PFOS were calculated.The result indicates that the ability of accepting electron of neutral PFOS is larger than that of anionic PFOS,while the electron excited by UV irradiation from HOMO to LUMO in the anionic PFOS is easier than that in the neutral PFOS.     

Theoretical investigation of substitution and end-group effects on poly(p-phenylene vinylene)s

Semi-empirical AM1 and ZINDO/S, as well as density function theory (DFT) method B3LYP/6-31G(d) quantum chemical calculations were carried out to study the electronic structures and optical properties of poly(p-phenylene vinylene) derivatives (PPVs) with 10 and 11 phenylene rings in the backbone. The calculations suggest that the assembly of alternate incorporation of CN and alkoxy substituted phenylene rings in the PPV backbone could be a good way to construct organic semiconductors with low HOMO/LUMO energy band-gaps. The effect of the end-group on the electronic structures and optical properties of the conjugated polymer was investigated by the calculated UV-Vis and UPS spectra. It was demonstrated that the aldehyde and phosphate end-groups have limited effects on the photophysical properties in the UV-visible range.     

Theoretical study of the optical gain characteristics of a Ge1-xSnx alloy for a short-wave infrared laser

Optical gain characteristics of Ge_(1_x)Snμx are simulated systematically.With an injection carrier concentration of 5×10~(18)/cm~3 at room temperature,the maximal optical gain of Ge_(0.922)Sn_(0.078) alloy(with n-type doping concentration being 5×10~(18)/cm~3) reaches 500 cm~(-1).Moreover,considering the free-carrier absorption effect,we find that there is an optimal injection carrier density to achieve a maximal net optical gain.A double heterostructure Ge_(0.554)Si_(0.289)Sn_(0.157)/Ge_(0.922)Sn_(0.078)/Ge_(0.554)Si_(0.289)Sn_(0.157) short-wave infrared laser diode is designed to achieve a high injection efficiency and low threshold current density.The simulation values of the device threshold current density J_(th)are 6.47 kA/cm~2(temperature:200 K,and λ=2050 nm),10.75 kA/cm~2(temperature:200 K,and λ=2000 nm),and23.12 kA/cm~2(temperature:300 K,and λ=2100 nm),respectively.The results indicate the possibility to obtain a Si-based short-wave infrared Ge_(1-x)Sn_x laser.     

Rapid Capillary-Assisted Solution Printing of Perovskite Nanowire Arrays Enables Scalable Production of Photodetectors

Despite recent progress in producing perovskite nanowires (NWs) for optoelectronics, it remains challenging to solution-print an array of NWs with precisely controlled position and orientation. Herein, we report a robust capillary-assisted solution printing (CASP) strategy to rapidly access aligned and highly crystalline perovskite NW arrays. The key to the CASP approach lies in the integration of capillary-directed assembly through periodic nanochannels and solution printing through the programmably moving substrate to rapidly guide the deposition of perovskite NWs. The growth kinetics of perovskite NWs was closely examined by in situ optical microscopy. Intriguingly, the as-printed perovskite NWs array exhibit excellent optical and optoelectronic properties and can be conveniently implemented for the scalable fabrication of photodetectors.