标准CMOS工艺载流子注入型三端Si-LED的设计与研制

采用无锡华润上华(CSMC) 0.5 μm 标准CMOS工艺,设计并制备了一种新型的高发光功率载流子注入型三端Si-LED器件。该器件在p型衬底上进行n⁺掺杂,与p衬底形成两个相对的n⁺p结,其中一个结正向偏置,发出峰值波长在1 100 nm附近的红外光;另一个结同样正偏,作为注入结对发光进行调制。测试结果显示:第三端注入载流子明显增强了总体的发光功率,在10 mA偏置电流、3 V调制电压下,可获得1 nW的光功率,与单结相比提高了两个数量级。由于工作电压低,该器件可与目前主流的CMOS工艺共电源单芯片集成,在光电集成领域具有一定的应用前景。     

用光伏效应研究有机薄膜电致发光器件中的接触性质

首次发现了有机薄膜电致发光器件的光生伏特效应，通过对器件的光电流响应谱的详细研究，分析了不同结构的有机发光器件中的有机半导体之间，以及有机半导体与电极材料之间的半导体接触性质，发现有机发光材料Ａｌｑ３，有机空穴传输材料ｄａｉｍｉｎｅ与金属铝电极之间形成阻挡接触，是电致发光器件发光和产生光电效应的根本原因；而双层器件中有机层Ａｌｑ３与ｄｉａｍｉｎｅ之间的结是双层器件产生高发光效率的原因，正是这种结在双层器件中起了局限载流子和激子的作用，使发光亮度大为提高，结合分区掺杂实验结果，给出了较完善的能带模型．     

一种新型SOI Mach-Zehnder干涉型电光调制器的设计

在超紧缩双曲锥形3dB多模干涉耦合器的基础上,设计了一种新的Silicon-on-insulator (SOI) Mach-Zehnder干涉型电光调制器.与传统的Y分支器相比,双曲锥形3dB耦合器的制作容差大,而长度缩短了近30%,使得整个器件的尺寸大幅减小.调制区采用横向注入的PIN结构,模拟结果表明:当外加偏压为0.86V时,器件的调制深度最大,此时注入电流为13.2mA,对应的器件功耗为11.4mW.     

用光伏效应研究有机薄膜电致发光器件中的接触性质

首次发现了有机薄膜电致发光器件的光生伏特效应,通过对器件的光电流响应谱的详细研究,分析了不同结构的有机发光器件中的有机半导体之间,以及有机半导体与电极材料之间的半导体接触性质,发现有机发光材料Alq3,有机空穴传输材料daimine与金属铝电极之间形成阻挡接触,是电致发光器件发光和产生光电效应的根本原因,而双层器件中有机层Alq3与diamine之间的结是双层器件产生高发光效率的原因,正是这种结在双层器件中起了局限载流子和激子的作用,使发光亮度大为提高,结合分区掺杂实验结果,给出了较完善的能带模型。     

Vertical-cavity saturable-absorber intensity modulator

We propose and demonstrate a reflection-type optical modulator, with surface-normal architecture, that exploits the optical saturation of absorption in semiconductor quantum wells. The modulation section of the modulator, which is composed of quantum wells placed within a Fabry-Perot cavity, is optically controlled by an intensity-modulated beam generated by an in-plane laser integrated monolithically on the same wafer and grown in a single epitaxial step. The modulation section and the in-plane laser share the same medium; therefore, efficient coupling between the control beam and the signal beam is achieved. The device was successfully used for active mode locking of an erbium-doped fiber laser.     

Development and Performance Analysis of a Photonics-Assisted RF Converter for 5G Applications

This article presents a simple, ultra-wideband and tunable radiofrequency (RF) converter for 5G cellular networks. The proposed optoelectronic device performs broadband photonics-assisted upconversion and downconversion using a single optical modulator. Experimental results demonstrate RF conversion from DC to millimeter waves, including 28 and 38 GHz that are potential frequency bands for 5G applications. Narrow linewidth and low phase noise characteristics are observed in all generated RF carriers. An experimental digital performance analysis using different modulation schemes illustrates the applicability of the proposed photonics-based device in reconfigurable optical wireless communications.     

Pure spin currents generation in magnetic tunnel junctions by means of adiabatic quantum pumping

We study the spin polarized currents generation in a magnetic (ferromagnetic/ferromagnetic) tunnel junction by means of adiabatic quantum pumping. Using a scattering matrix approach, it is shown that a pure spin current can be pumped from one ferromagnetic lead into the adjacent one by adiabatic modulation of the magnetization and the height of the barrier at the interface in absence of external bias voltage. We numerically study the characteristic features of the pure spin current and discuss its behavior for realistic values of the parameters. We show that the generated pure spin current is robust with respect to the variation of the magnetization strength, a very important feature for a realistic device, and that the proposed device can operate close to the optimal pumping regime. An experimental realization of a pure spin current injector is also discussed.     

A novel wide-dynamic-range logarithmic-response bipolar junction photogate transistor for CMOS imagers

In this paper, a new photodetector, bipolar junction photogate transistor (BJPG), is proposed for CMOS imagers. Due to an injection p+n junction introduced, the photo-charges drift through the p+n junction by the applied electronic field, and on the other hand, the p+n junction injects the carriers into the channel to carry the photo-charges. Therefore this device can increase the readout rate of the pixel signal charges and the photoelectron transferring efficiency. Using this new device, a new type of logarithmic pixel circuit is obtained with a wide dynamic range which makes photo-detector more suitable for imaging the naturally illuminated scenes. The simulations show that the photo current density of BJPG increases logarithmically with the incident light power due to the introduced injection p+n junction. The noise characteristics of BJPG are analyzed in detail and a new gate-induced noise is proposed. Based on the established numerical analytical model of noise, the power spectrum density curves a     

Integrated Electro-Absorption Modulation DFB Laser Based Optical True Time-Delay Feeder for X-Band Phased Array Antennas

A 4-bit optical true-time-delay feeder incorporating an integrated electro-absorption modulation distributed feedback (DFB) laser for X-band phased array antennas is demonstrated. The integrated electro-absorption modulation DFB laser is an attractive device that provides a very compact, low-cost solution for optical true-time-delay systems. The variable delay line is constructed by cascaded magneto-optic switches, which have fast switching speed. The integrated electro-absorption modulation DFB laser system shows high signal-to-noise ratio up to 58dB, and the transmission performance of the system is relatively good and accredited.     

Numerical simulation of the modulation transfer function in planar InGaAs dense arrays

Three-dimensional simulation methodology has been used to evaluate the performance of lattice matched InGaAs/InP double layer planar heterointerface detector arrays. The device characteristics under optical illumination and dark conditions have been computed. The modulation transfer function (MTF) profiles have been calculated with varying device geometries and carrier dynamics. It is found that the p well diffusion radius and minority carrier recombination play important roles in the MTF behaviors of dense arrays. Moderate p well diffusion dimension should be used to balance the device performances between the dark current and MTF profile. Moreover, better MTF characteristic under low light condition can be achieved with higher quality material which has longer recombination lifetime. The influences of underlying mechanisms including photon generated carriers diffusion and carrier recombination processes have been discussed. These simulation methods and results should provide a useful tool for the evaluation and improvement of imaging power of InGaAs focal plane arrays.     

Design and Analysis of the Integrated Plasma Wave Micro-Optical Modulator/Switch

Feasibility of a new integrated amplitude modulator/switch operating up to the visible spectrum, based on the absorption of light due to the linear interaction of the incident laser and a two-dimensional plasma layer is demonstrated. Plasma layers are generated via the Muller effect at the waveguide's interfaces. A plasma wave is excited in the two-dimensional gas when it is illuminated by electromagnetic radiation. Thus, due to the energy transfer from the electromagnetic wave to the plasma wave, the output light intensity can be controlled. The device is capable of amplitude modulation of guided beams in dielectric waveguides. Analysis based on both full-classical and semiclassical approaches are performed and are compared.     

Electro-optic adiabatic wavelength shifting and Q switching demonstrated using a p-i-n integrated photonic crystal nanocavity

We demonstrate adiabatic wavelength shifting by electro-optic modulation, using a p-i-n integrated high-Q photonic crystal nanocavity. The wavelength of the trapped light is adiabatically shifted by modulating the resonance of the cavity faster than the photon lifetime. The cavity resonance is changed by injecting electrons through a p-i-n junction to reduce the refractive index. In addition, we employ adiabatic wavelength shifting in a demonstration of dynamic Q tuning by electro-optic modulation.     

Ultrafast all-optical modulation by near-infrared intersubband transition in n-doped InGaAs/AlAsSb quantum wells

We demonstrate the ultrafast modulation of interband (IB)-resonant light (1.0–1.1 μm) by near-infrared intersubband (ISB)-resonant light (1.55–1.9 μm) in n-doped InGaAs/AlAsSb multiple quantum wells (QWs) using non-degenerate pump–probe spectroscopy. A modulation with an absorption recovery time of 1.0–2.0 ps has been observed in a planer-type modulation device due to ultrafast ISB relaxation of the carriers. The IB carrier relaxation process in the absence of an ISB-resonant light has also been investigated by time-resolved photoluminescence (PL) measurement. The modulation speed is determined by the inter- and intra-subband relaxation of the carriers in the conduction subband. The modulation speed at 1.1 μm due to an ISB-resonant pump light at 1.95 μm has been observed to be 1.4 ps at excitation energy of 500 fJ/μm².     

Modulation depth of series SQUIDs modified by Josephson junction area

The superconducting quantum interference device(SQUID) amplifier is widely used in the field of weak signal detection for its low input impedance, low noise, and low power consumption. In this paper, the SQUIDs with identical junctions and the series SQUIDs with different junctions were successfully fabricated. The Nb/Al-AlO_x/Nb trilayer and input Nb coils were prepared by asputtering equipment. The SQUID devices were prepared by a sputtering and the lift-off method.Investigations by AFM, OM and SEM revealed the morphology and roughness of the Nb films and Nb/Al-AlO_x/Nb trilayer.In addition, the current–voltage characteristics of the SQUID devices with identical junction and different junction areas were measured at 2.5 K in the He~3 refrigerator. The results show that the SQUID modulation depth is obviously affected by the junction area. The modulation depth obviously increases with the increase of the junction area in a certain range. It is found that the series SQUID with identical junction area has a transimpedance gain of 58 ? approximately.     

Approach to all-optical bipolar direct-sequence ultrawideband coding

An approach to all-optical bipolar direct-sequence ultrawideband (UWB) encoding for multiple access communications is proposed and demonstrated. The bipolar coding is performed based on electro-optic phase modulation and phase modulation to intensity modulation (PM-IM) conversion in a fiber Bragg grating (FBG) array that serves as a multichannel frequency discriminator. The chip number and the chip period of the code are determined by the number of FBGs and their physical separation. By locating the optical carriers that carry a Gaussian pulse at the left or right slopes of the FBG reflection spectra, bipolar direct-sequence UWB codes are generated. A bipolar UWB coding system with a code length of 4 is experimentally demonstrated.     

具有P型覆盖层新型超级结横向双扩散功率器件

为了设计功率集成电路所需要的低功耗横向双扩散金属氧化物半导体器件(lateral double-diffused MOSFET), 在已有的N型缓冲层超级结LDMOS(N-buffered-SJ-LDMOS)结构基础上, 提出了一种具有P型覆盖层新型超级结LDMOS结构(P-covered-SJ-LDMOS). 这种结构不但能够消除传统的N沟道SJ-LDMOS由于P型衬底产生的衬底辅助耗尽问题, 使得超级结层的N区和P区的电荷完全补偿, 而且还能利用覆盖层的电荷补偿作用, 提高N型缓冲层浓度, 从而降低了器件的比导通电阻. 利用三维仿真软件ISE分析表明, 在漂移区长度均为10 μm的情况下, P-covered-SJ-LDMOS的比导通电阻较一般SJ-LDMOS结构降低了59%左右, 较文献提出的N型缓冲层 SJ-LDMOS(N-buffered-SJ-LDMOS)结构降低了43%左右.     

A novel structure of a high current gain 4H-SiC BJT with a buried layer in base

In this paper, a new structure of a 4H-SiC bipolar junction transistor (BJT) with a buried layer (BL) in the base is presented. The current gain shows an approximately 100% increase compared with that of the conventional structure. This is attributed to the creation of a built-in electric field for the minority carriers to transport in the base which is explained based on 2D device simulations. The optimized design of the buried layer region is also considered by numeric simulations.     

Thermal characteristics analysis of an IGBT using a fiber Bragg grating

This paper proposes a new method to develop a thermal model of an insulated gate bipolar transistor (IGBT) employing an optical fiber sensor mounted on the chip structure. Some features of the sensor such as electromagnetic immunity, small size and fast response time, allow the identification of temperature changes generated by the energy loss during device operation through direct measurement. In fact, this measurement method is considered impossible with conventional sensors. The online monitoring of the junction temperature enables identify the thermal characteristics of the IGBT. The results are used to develop an accurate model to simulate the heat generated during the device conduction and switching processes. The model showed a difference of only 0.3% between the measured and simulated results, besides allowing evaluate separately the heat generated by each turn-ON/OFF process.     

Optical orthogonal frequency division multiplexed transmission using all‐optical discrete Fourier transform

Orthogonal frequency division multiplexing (OFDM) can provide spectrally efficient communication channels because it can utilize carrier orthogonality and various impairment mitigation methods. An optical OFDM signal can be generated electronically to multiplex lower‐rate carriers. In recent advancements, OFDM signals are also shown to be generated and demultiplexed by all‐optical discrete Fourier transform (DFT), overcoming the speed limit of electronics for >Tbps capacity. High‐performance DFT devices, such as arrayed waveguide grating (AWG) or planar lightwave circuit (PLC), are critically required to obtain strong orthogonality for scalable all‐optical OFDM (AO‐OFDM) system implementations. Advanced techniques such as coherent modulation and detection with digital impairment mitigation are also important for long‐reach AO‐OFDM transmissions. More recently, optical superchannel schemes have been introduced utilizing coherent detection for multi‐Tbps AO‐OFDM transmissions. This paper reviews the device and system aspects for the AO‐OFDM technology, including a generalized theoretical model to provide an indepth understanding.     

结温对DCJTB混合YAG∶Ce3+白光LED光谱特性的影响

研究了结温变化对DCJTB混合YAG∶Ce3+荧光粉的白光LED光谱特性的影响。采用分层点粉的方法,在LED芯片上分层涂覆YAG荧光粉和有机材料DCJTB,可以使器件的显色指数高达90。利用实验室自行研发的一体化LED散热支架可方便准确测量出结温。实验表明：结温升高使蓝光芯片辐射幅值不断下降,YAG荧光粉被激发所辐射的黄光辐射幅值先增大后减小,红光光谱发生蓝移,器件的显色指数呈线性下降,色温先增大后减小。