A new circuit model of HgCdTe photodiode for SPICE simulation of integrated IRFPA

We propose a novel sub circuit model to simulate HgCdTe infrared photodiodes in a circuit simulator, like PSPICE. We have used two diodes of opposite polarity in parallel to represent the forward biased and the reverse biased behavior of an HgCdTe photodiode separately. We also connected a resistor in parallel with them to represent the ohmic shunt and a constant current source to represent photocurrent. We show that by adjusting the parameters in standard diode models and the resistor and current values, we could actually fit the measured data of our various HgCdTe photodiodes having different characteristics. This is a very efficient model that can be used for simulation of readout integrated circuit (ROIC) for HgCdTe IR photodiode arrays. This model also allows circuit level Monte Carlo simulation on a complete IRFPA at a single circuit simulator platform to estimate the non-uniformity for given processes of HgCdTe device fabrication and Si ROIC fabrication.     

Potential frequency bandwidth estimation of TO packaging techniques for photodiode modules

Scattering parameters of photodiode chip, TO header and TO packaged module are measured, and the effects of TO packaging network on the high-frequency response of photodiode are investigated. Based on the analysis, the potential bandwidth of TO packaging techniques is estimated from the scattering parameters of the TO packaging network. Another method for estimating the potential bandwidth from the equivalent circuit for the TO packaged photodiode model is also presented. The results obtained using both methods show that the TO packaging techniques used in the experiments can potentially achieve a frequency bandwidth of 22 GHz.     

Self-calibration of Silicon Photodiode in the Soft X Ray Spectral Range

Self-calibration experiment of silicon photodiodes in the soft X-ray spectral region of synchrotron radiation (50—2000eV) is carried out. Because of elimination of “dead region” and adoption of very thin SiO₂ layer as window of the silicon photodiode, a simple model can be used to analyze the process. Based on parameters measured by experiment, the quantum efficiency of the silicon photodiode is calculated, and the flux of incident synchrotron radiation is also obtained.     

Computer modeling of carrier transport in PbSnSe photodiodes

A numerical technique has been used to solve the carrier transport equations for n⁺−p Pb_0.935Sn_0.065Se photodiode configuration. The model computes the spatial distribution of the electric field, electron and hole concentrations and the generation-recombination mechanisms. Also the effect of doping profiles on the photodiode parameters (R₀A product, quantum efficiency) is analysed. Results of calculations indicate the potential possibilities of constructing higher quality PbSnSe photodiodes. The R₀A product of experimentally measured PbSnSe photodiodes is controlled by Shockley-Read generation-recombination mechanisms.     

Investigation of a Relativistic Magnetron Supplied from a High-Current Linear Induction Accelerator

The physical processes in a system relativistic microwave generator - power supply unit with a strong feedback are investigated. A computer model is constructed to calculate the output parameters of these systems substituted by equivalent circuits. A model is constructed for a linear induction accelerator based on magnetic elements intended for operation with relativistic magnetrons the nonlinear units of the equivalent circuit of which are calculated in the context of the theory of average motion.     

A flexible blue light sensitive organic photodiode with high properties for the applications in low‐voltage‐control circuit and flexion sensors

Low‐voltage‐control circuit is one of the most important parts of the modern electrical control system due to the avoidance of operation risk and easy automation. Here, based on a C₆₀: m‐MTDATA bulk heterojunction, a blue‐light‐sensitive organic photodiode (OPD) is explored for the development of flexible low‐voltage‐control circuit. The control of circuit under 2000 V high voltage is achieved. The influences of the organic‐layer thickness, the donor/acceptor volume ratio and the matching of energy levels on the photocurrent are investigated. The maximum light/dark current ratio and current transfer ratio of 1.3 × 10⁴ and 1.3% are achieved, respectively. The highest photoresponse is up to 130 mA/W, markedly higher than some commercial inorganic photodiodes. This device could also be used as flexion and mechanical force sensors with the current density changing under different bending conditions. Therefore, this sort of OPD has a promising application in low‐voltage‐controlled, high‐voltage‐endurable hands for intelligent robots.     

Characterization and optimization of high-power InGaAs/InP photodiodes

The performance of 34-μm-diameter InGaAs/InP charge compensated modified uni-traveling carrier photodiodes (CC MUTCs) is studied using a commercial device simulator based on a drift-diffusion model. Excellent agreement has been achieved between simulations and experiments. The origin of the degradation of responsivity at high optical injection level is investigated. Parameters of the photodiode are further optimized to maximize the saturation current without sacrificing bandwidth and responsivity.     

Ultralow-noise near-infrared detection system with a Si p-i-n photodiode

Noises associated with materials and devices in the readout circuits for a Si p-i-n photodiode have been measured. The dielectric polarization noise of the materials and devices near the gate circuit of the junction field-effect transistor used for the preamplifier determined the photodetection limits of photodiodes with a diameter smaller than several millimeters. We fabricated an ultralow-noise photodetection system, minimizing the polarization noise as much as possible. The readout noises of the system were 10 and 18 electrons in a correlated double sample for 0.1- and 1-mm-diameter Si p-i-n photodiodes at 77 K, respectively.     

用于红外单光子探测的雪崩光电二极管传输线抑制电路模型的理论分析

结合利用雪崩光电二极管(APD)进行红外单光子探测电路模型的工作原理和特点以及传输线瞬态电脉冲产生的过程,提出了将传输线瞬态过程脉冲发生电路模型用于APD雪崩抑制的一种新方法,该方法可以实现利用APD门模工作方式进行红外单光子探测的过程.主要从理论上计算了红外单光子信号入射APD时,传输线脉冲发生电路模型中负载电阻输出电脉冲的特点,讨论了传输线终端不同边界条件对输出电脉冲的影响,通过理论计算确定了这种利用APD进行红外单光子探测新模型的电路结构与参数,证明了该电路模型用于红外单光子探测APD门模工作方式的 关键词： 红外单光子探测技术 雪崩光电二极管(APD) 抑制电路 传输线瞬态过程     

In-situ electrical characterisation of a photodiode during nano-structuring with a focussed ion beam

We study the fabrication and power conversion efficiency of GaAs photodiodes, which have been nano-structured and covered with colloidal quantum dots. A focussed ion beam is used to etch vertical channels into the photodiodes and the detrimental effects of this treatment are characterised in-situ during the fabrication process. A novel experimental configuration allows the electrical characterization of the photodiodes under laser illumination during the nano-fabrication process and reveals the gradual decrease of the photodiodes’ shunt resistance with increasing laterally revealed surface along the etched channels. This is interpreted as evidence for leakage currents through redeposited material and surface states on the lateral channel surface. After the fabrication step the channels are filled with colloidal quantum dots, which upon absorption of light transfer electronic excitations to the photodiode via resonance energy transfer. It is found that after the addition of quantum dots the nano-structured photodiodes show larger enhancements of the energy conversion efficiency under simulated solar irradiance than the pristine photodiodes. Nevertheless, the device degradation induced by the ion beam treatment itself cannot be compensated for.     

光通信用雪崩光电二极管(APD)频率响应特性研究

吸收层、电荷层和倍增层分离结构雪崩光电二极管(SACM-APD),包括InP/InGaAs、InAlAs/InGaAs和Si/Ge APD是光通信领域近年来研究的热点. 本文基于电路模型,系统比较了不同外延层厚度、不同材料以及不同结构APD的频率响应特性,重点探讨Si/Ge APD吸收层厚度、光敏面大小、寄生参数等各项参数对带宽的影响,仿真结果与实际器件实验数据相符合. 本文的研究成果对SACM-APD的优化设计具有指导意义. 关键词： SACM-APD 电路模型 频率响应     

荷控忆阻器等效电路分析模型及其电路特性研究

忆阻器是物理上新实现的具有记忆特性的基本二端电路元件. 根据φ-q关系式的泰勒级数形式构建了荷控忆阻器等效电路分析模型, 以三次非线性荷控忆阻器模型为例, 对不同参数条件下的荷控忆阻器进行了伏安关系、有无源性等电路特性的理论分析. 结果表明: 荷控忆阻器的伏安关系具有斜体“8”字形紧磁滞回线特性, 随其参数符号的不同, 荷控忆阻器呈现出无源性和有源性, 导致其电路特性发生相应的变化; 相比无源荷控忆阻器, 有源荷控忆阻器更适用于作为二次谐波信号产生电路使用. 制作了荷控忆阻器特性分析等效电路的实验电路, 实验测量结果很好地验证了理论分析结果. 关键词： 荷控忆阻器 等效电路 伏安关系 电路特性     

Electrical characteristic signatures for non-uniformity analysis in HgCdTe photodiode arrays

In this paper we present a method of analyzing the performance non-uniformity of HgCdTe photodiode arrays for infrared imaging applications. For quantifying the characteristic behavior of various photodiodes, we have parametrized the dynamic resistance verses voltage signatures in such a way that the obtained signature parameters have some relevance with different physical parameters. We also estimated the sensitivity of the proposed signatures on physical parameters using statistical technique. These characteristics signatures may be used to quantify the non-uniformity of the HgCdTe photodiodes in IR imaging arrays and its analysis. The method presented here is based on theoretical calculation of MWIR HgCdTe photodiodes. However, the method is generic and may be implemented on any other type of diode arrays for theoretical or experimental analysis of their non-uniformity.     

高速光探测器封装的优化设计

提出了一种高速光探测器封装优化设计的新方法。首先用矢量网络分析仪对封装寄生参量和探测器芯片进行准确测量,研究了探测芯片的本征参量与封装寄生参量之间的谐振现象,然后合理利用这种谐振效应对芯片的频率响应特性进行有效补偿。理论分析和实验结果都证明优化封装后器件的频率响应带宽超过了芯片的响应带宽。该方法不需要另加其它元件．而仅仅利用光电器件封装过程中必不可少的金丝所带来的寄生电感,就达到了改善器件频率响应特性的目的。     

用于压缩光探测的高共模抑制比平衡零拍探测器

根据光电二极管的等效电路图,基于自减方案的平衡零拍探测器的光电管(ETX500)产生的光电流的位相差异主要由等效电容引起,通过给两个光电管施加不同的偏置电来补偿等效电容的差异获得高共模抑制比的平衡零拍探测器,在探测器中安装任意两个ETX500,获得了63.8dB的高共模抑制比,并且当激光功率达到探测器的饱和功率54 mW时,激光光场的噪声谱在2 MHz处高于电子学噪声37dB,该探测器能很好地满足压缩态探测对低噪声、线性增益及高共模抑制比的要求。     

Design and fabrication of multi-channel photodetector array monolithic with arrayed waveguide grating

We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13-channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometry and refractive index. Aseamless joint structure has been designed and fabricated for integrating the output waveguides of AWGs with the evanescently coupled waveguide photodiode array. The highest simulation quantum efficiency could achieve 92% when the matching layer thickness of the PD is 120 nm and the insertion length is 2 μm. The fabricated PD with 320-nm-thick matching layer and 2-μm-length insertion matching layer present a responsivity of 0.87 A/W.     

Signatures of differential Log R–V characteristics for non-uniformity analysis of HgCdTe infrared photodiode arrays

In continuation to our research on the non-uniformity in infrared focal plane arrays of HgCdTe photodiodes, we have examined and found a few important signature parameters in the forward bias region of the electrical characteristics of the photodiodes. These signatures are the peaks of the first and second order derivatives of dynamic resistance–voltage characteristics. They show good correlation with the material and devices parameters and have been investigated to be good signatures for statistical performance variation analysis. In this note, by using theoretical model and statistical analysis of these signatures, we show that the variations in the proposed signatures represent underlying non-uniformity in important material/device parameters. Such signatures may be used along with the other conventional signatures of reverse biased photodiode characteristics to identify the root cause of response non-uniformity in the array with high confidence level.     

基于三端口网络模型的折叠波导行波管注波互作用理论研究

将周期性慢波结构中的单元结构等效为一个三端口网络,利用高频结构模拟软件确定等效模型的参数,由此建立了一种通用的慢波结构等效模型.该方法不需要进行复杂的电路等效,直接由高频软件得到通道内场分布,因此较解析方法简单,又不像等效线路模型那么烦琐.基于该三端口网络模型,建立了适用于折叠波导行波管的一维注波互作用非线性理论模型,编写了数值计算程序,对一支折叠波导行波管进行了模拟.该理论模型模拟的结果与实验结果误差小于10%.该理论模型可以用于指导新型折叠波导行波管的设计及非线性模拟研究.     

Modelling nonlinearity in piezoceramic transducers: From equations to nonlinear equivalent circuits

Quadratic nonlinear equations of a piezoelectric element under the assumptions of 1D vibration and weak nonlinearity are derived by the perturbation theory. It is shown that the nonlinear response can be represented by controlled sources that are added to the classical hexapole used to model piezoelectric ultrasonic transducers. As a consequence, equivalent electrical circuits can be used to predict the nonlinear response of a transducer taking into account the acoustic loads on the rear and front faces. A generalisation of nonlinear equivalent electrical circuits to cases including passive layers and propagation media is then proposed. Experimental results, in terms of second harmonic generation, on a coupled resonator are compared to theoretical calculations from the proposed model.