Electron transit time of PIN photodiodes fabricated in two-valley semiconductors

Electron transit time was calculated for a PIN photodiode with the absorption layer realized in two-valley semiconductor (GaAs, InGaAs...). Non-stationary effects and changes of the electric field along the layer result in a dependence of the electron transit time on both the applied voltage and the thickness of the layer. This dependence shows marked maximum and minimum, which could be important when modelling the response times of PIN photodiodes fabricated in these materials.     

Numerical Estimations of Carrier Generation–Recombination Processes and the Photon Recycling Effect in HgCdTe Heterostructure Photodiodes

An enhanced computer program has been applied to explain in detail the photon recycling effect which drastically limits the influence of radiative recombination on the performance of p-on-n HgCdTe heterostructure photodiodes. The computer program is based on a solution of the carrier transport equations, as well as the photon transport equations for semiconductor heterostructures. We distinguish photons in two energy ranges according to p ⁺ and n region with unequal band gaps. As a result, both the distribution of thermal carrier generation and recombination rates and spatial photon density distribution in photodiode structures have been obtained. The general conclusion, similar to our earlier work concerning 3-μm n-on-p HgCdTe heterostructure photodiodes, confirms the previous assertion by Humphreys that radiative recombination does not limit HgCdTe photodiode performance.     

Short-wavelength infrared array avalanche photodetectors on the basis of InGaAs heteroepitaxial structures

SWIR ADP 320 × 256 FPAs based on p–i–n photodiodes in InGaAs heterostructures have been developed and investigated. The typical InGaAs/InP PIN heterostructures are formed by Metal Organic Vapor Phase Epitaxy (MOVPE) on n⁺ type InP substrates. The InGaAs/InP PIN photodiodes performance have been estimated by measuring current-voltage characteristics. APD arrays are designed using a mesa-passivated avalanche photodiode device array of p–i–n junctions in heterostructure with common absorption and multiplication regions. The optimal operating point for managing avalanche application depended on various factors has been started at 15 V bias and the multiplication coefficient was of 2–4.     

应用于自由空间光通信的PIN激光信号阵列接收器

针对目前的自由空间光通信存在空间光-光纤难以 有效耦合这一问题,考虑到空间光耦合进入光纤后需要将光信号转换为电信号才能实现通信 ,为此本 文提出直接将空间光信号转换为电信号的思想,设计了一种应用于空间光通信的PIN光电二 极管阵列接收器,每一个PIN光电二极管可 以独立接收空间激光并将其转换为电信号,多个PIN光电二极管通过串联和并联将电信号汇 合以方便后续信号处理。对这一新的接收器进行理论分析和模拟实验的结果表明,新的接收 器能有效提高空间光的接收效率。     

光通信中的主流光电探测器研究

对光通信系统解复用接收部分中的关键器件——主流光电探测器进行综合比较、优缺点分析与展望．分别对PIN光电探测器,普通雪崩二极管,超品格雪崩二极管,波导型光电探测器,振腔增强型光电探测器,金属-半导体-金属光电探测器的原理和特点做了简要概括,并做系统比较,最后对光电探测器发展前景进行展望．     

The impact of a large bandgap drift region in long-wavelengthmetamorphic photodiodes

A comparative study of two types of metamorphic double heterojunction long-wavelength photodiodes on GaAs substrates is performed in terms of their bandwidths and responsivities. A p-i-i-n heterostructure with a large bandgap drift layer (I-InAlAs) at the cathode end of the photoabsorption region (i-InGaAs) is compared experimentally and theoretically to a p-i-n structure without a drift layer. Both types of photodiodes were fabricated using an InGaAs-InGaAlAs-InAlAs double heterostructure design to simultaneously achieve high bandwidths and high responsivities. The inclusion of an I-InAlAs drift region resulted in p-i-i-n photodiodes with larger bandwidths than p-i-n photodiodes with the same areas, or conversely a p-i-i-n photodiode can be made larger than a comparable p-i-n photodiode, but achieve the same bandwidth. Therefore, p-i-i-n photodiodes provide larger optical fiber alignment tolerances and better coupling efficiency than p-i-n photodiodes with the same bandwidths, p-i-i-n photodiodes with 10-μm-diameter optical windows typically exhibited low dark currents of 500 pA at 5-V bias, responsivities of 0.6 A/W, and a -3-dB bandwidth of 38 GHz for 1.55-μm operation     

High-speed Schottky photodiode on semi-insulating GaAs

A high-speed GaAs photodiode has been fabricated on a GaAs semi-insulating substrate. The photodiode has an active area of 8 ?m × 15 ?m and a bandwidth in excess of 9 GHz. This Schottky photodiodes is suitable for monolithic integration with other optoelectronic components.     

一种改进结构的GaAs微波PIN二极管

设计并制作了高性能GaAs微波PIN二极管.分析了GaAsPIN二极管的结构对其性能的影响,并根据分析结果改进了GaAsPIN二极管的结构.制作了常见结构和改进结构的GaAsPIN二极管,比较了不同结构的GaAsPIN二极管的测试数据,从而验证了理论分析的结果.改进后的GaAsPIN二极管制作工艺更为简单,具有良好的高频特性,截止频率达到1520.5GHz.这种改进结构的GaAs微波PIN二极管在微波电路中具有良好的应用前景.     

Numerical modeling of energy balance equations in quantum well AlxGa1-xAs/GaAs p-i-n photodiodes

The energy balance equations coupled with drift diffusion transport equations in heterojunction semiconductor devices are solved modeling hot electron effects in single quantum well p-i-n photodiodes. The transports across the heterojunction boundary and through quantum wells are modeled by thermionic emission theory. The simulation and experimental current-voltage characteristics of a single p-i-n GaAs/Al _xGa_1-xAs quantum well agree over a wide range of current and voltage, The GaAs/Al_xGa_1-xAs p-i-n structures with multi quantum wells are simulated and the dark current voltage characteristics, short circuit current, and open circuit voltage results are compared with the available experimental data, In agreement with the experimental data, simulated results show that by adding GaAs quantum wells to the conventional cell made of wider bandgap Al_x Ga_1-xAs, short circuit current is improved, but there is a loss of the voltage of the host cell, In the limit of radiative recombination, the maximum power point of an Al_0.35Ga_0.65As/GaAs p-i-n photodiode with 30-quantum-well periods is higher than the maximum power point of similar conventional bulk p-i-n cells made out of either host Al_0.35Ga_0.65As or bulk GaAs material     

Low dark current GaAs metal-semiconductor-metal (MSM) photodiodes using WSixcontacts

We present the fabrication and characterization of metal-semiconductor-metal (MSM) photodiodes using the same undoped GaAs layer that is used as a buffer layer in the epitaxial structure for GaAs field effect transistors (FET's). To study the dark current mechanism, various metal electrodes used for Schottky contacts are examined. A drastic V-shape relationship between the dark current of MSM photodiode and the Schottky barrier height is found. An extremely low dark current (a few nanoamperes) in the MSM photodiode is obtained by using tungsten silicide as electrode metal. It is concluded that the dark current is a function of a rivalry relation between the electron injection at the cathode and the hole injection at the anode. The internal gain of the MSM photodiode with tungsten silicide contacts is found, and possible mechanisms are discussed. A flat frequency response up to 1.3 GHz is obtained. The results shows the feasibility of MSM photodiodes for use as photodetectors with low minimum detectable power, and their applicability to monolithic integration with FET circuits.     

探测器非线性对微波光子链路性能的影响

提出了一种新的光电探测器（PD）非线性模型,进而分析了PD非线性对系统增益及三阶无杂散动态范围（SFDR3）的影响。实验表明,当调制器的直流偏置角变化时,含PD非线性的实际链路与忽略PD非线性的理想链路相比,信号增益的最大值将下降1．7dB,SFDR3最大值下降3dB,因此在高性能链路中考虑探测器非线性是十分必要的。     

Measurement of very-high-speed photodetectors with picosecond InGaAsP film lasers

The impulse responses of very-high-speed photodiodes are determined using 5?15 ps pulses from optically pumped ultrashort-cavity film lasers operating between wavelengths of 1.15 ?m and 1.54 ?m. The measured response time (FWHM) for a back-illuminated InGaAs/InP punch-through PIN photodiode is 30 Ps.     

Experimental investigation on nonlinearities of PIN photodiodes

In this report, we experimentally investigate nonlinearity of PIN photodiode as a function of incident light power with different bias. It is found that the nonlinearity can be related with effective resistance of this device itself. According to ambipolar diffusion model, the resistance is divided into two parts, i.e. intrinsic region resistance and series resistance originating from non-Ohmic contact. Forward Current (I_f)-Voltage(V_f) plots indicate that fabrication of high-quality Ohmic contact is necessary to improve linear performance for PIN photodiodes.     

Monolithic PIN/preamplifier circuit integrated on a GaAs substrate

An AlGaAs/GaAs PIN photodiode and a GaAs transimpedance amplifier including six FETs have been monolithically integrated on a GaAs substrate. A photoreceiver operation exhibiting an excellent linearity has been demonstrated. The photodiode sensitivity of 0.44 A/W and the amplifier transimpedance of 1.0 × l04 V/A have been determined from the measurement.     

Assessment of approximate balance equation transport models used for submicron silicon device modelling

The common approximations found in literature for the balance equation method used for non-stationary submicron device simulation are presented and discussed. To assess different approximations, the full balance equation model is solved numerically solved for the n⁺-i-n⁺ submicron silicon structure where nonstationary transport effects eventually take place. The results obtained from the derived approximate models applied to the same silicon structure are compared with those obtained from the full model. In all cases, empirical formulae for momentum and energy relaxation times are used to clarify only the effect of approximations on the simulation results.     

Transient simulation of resonant cavity enhanced heterojunctionphotodiodes

The transient response of heterojunction photodiodes under pulse illumination has been simulated. By solving discretized time dependent drift-diffusion and Poisson equations, the local potential and carrier concentrations are computed at each time step. The device-level simulation is carried out by a circuit simulator in which localized carrier transport is modeled by circuit elements such as voltage controlled current sources, capacitors, and resistors. Results on conventional AlGaAs/GaAs and resonant cavity enhanced (RCE) GaAs/InGaAs heterojunction p-i-n photodiodes are presented. For a 10-μm×10-μm area detector, more than 40% bandwidth improvement along with a two-fold increase in the efficiency is predicted for RCE devices over optimized conventional photodiodes     

实用型5GHz带宽InGaAs／InP PIN光电探测器

设计并研制成功了实用型５ＧＨｚ带宽ＩｎＧａＡｓ／ＩｎＰ ＰＩＮ光电探测器，介绍了限制探测器响应速度的主要因素，微波封装的理论依据，以及所研制器件频率响应的测试结果。     

Modelling and characterization of the reverse recovery of ahigh-power GaAs Schottky diode

The reverse recovery characteristics of high-power GaAs Schottky rectifiers are reported at various temperatures; mixed device and circuit simulations were used to study the internal plasma dynamics during the reverse recovery process. In this approach, semiconductor transport and heat generation and diffusion equations were solved self-consistently using a two-dimensional (2-D) finite element grid structure under boundary conditions imposed by the measurement circuit. The simulation results are shown to be in good agreement with the measured data at temperatures in the range of 25°C to 125°C. These results are compared with the reverse recovery characteristics of a commercial silicon PIN power rectifier under identical conditions and it is shown that carrier depletion is the dominant mechanism causing the reverse recovery in a GaAs Schottky diode. The reverse recovery power loss is negligible in a GaAs Schottky rectifier and is shown to decrease as the case temperature is increased, contrary to the silicon PIN rectifier behaviour     

Unraveling the Gain Mechanism in High Performance Solution‐Processed PbS Infrared PIN Photodiodes

High gain and low dark current solution‐processed colloidal PbS quantum dots infrared (IR) PIN photodetectors with IR sensitivity up to 1500 nm are demonstrated. The low dark current is due to the P‐I‐N structure with both electron and hole blockers. The high gain in our IR photodiodes is due to the enhancement of electron tunneling injection through the 1,1‐bis[(di‐4‐tolylamino) phenyl]cyclohexane (TAPC) electron blocker under IR illumination resulting from a distorted electron blocking barrier in the presence of photo‐generated holes trapped in the TAPC electron blocker. It is further found that the trap states in the TAPC layer are generated by the Ag atoms penetrated in the TAPC layer during the thermal evaporation process. The resulting photodetectors have a high detectivity value of 7 × 10¹³ Jones, which is even higher than that of a commercial InGaAs photodiode.     

基于标准CMOS工艺的光敏传感单元结构的研究

基于0.6μm标准N阱CM O S工艺,研究了光敏管的结深及其侧墙结构对有源感光单元的感光面积百分比、光电响应信号幅值、感光灵敏度以及感光动态范围等参数的影响。研究了包括传统N+/P衬底的光敏管结构,以及网格状N+/P衬底,N阱/P衬底,网格状N阱/P衬底,P+/N阱/P衬底的光敏管结构。测试结果表明,不同深结深的光敏管结构,可以将器件感光灵敏度提高8~16.5 dB;网格状光敏管结构可以增加光敏管的侧墙面积,改善器件感光灵敏度;非网格状光敏管结构具有较低的暗电流和较大的感光动态范围,其中P+/N阱/P衬底光敏管结构的传感单元在变频两次扫描的工作方式下的感光动态范围可达139.8 dB。