Analysis of high-temperature performance of 4H-SiC avalanche photodiodes in both linear and Geiger modes

The high-temperature performance of 4H-SiC ultraviolet avalanche photodiodes(APDs)in both linear and Geiger modes is extensively investigated.During the temperature-dependent measurements,a fixed bias voltage is adopted for the device samples,which is much more practical and important for high-temperature applications.The results show that the fabricated 4H-SiC APDs are very stable and reliable at high temperatures.As the temperature increases from room temperature to 425 K,the dark current at 95%of the breakdown voltage increases slightly and remains lower than40 pA.In Geiger mode,our 4H-SiC APDs can be self-quenched in a passive-quenching circuit,which is expected for highspeed detection systems.Moreover,an interesting phenomenon is observed for the first time:the single-photon detection efficiency shows a non-monotonic variation as a function of temperature.The physical mechanism of the variation in hightemperature performance is further analyzed.The results in this work can provide a fundamental reference for researchers in the field of 4H-SiC APD ultraviolet detectors.

Planar InAlAs/InGaAs avalanche photodiode with 360 GHz gain×bandwidth product

This paper describes a guardring-free planar InAlAs/InGaAs avalanche photodiode(APD)by computational simulations and experimental results.The APD adopts the structure of separate absorption,charge,and multiplication(SACM)with top-illuminated.Computational simulations demonstrate how edge breakdown effect is suppressed in the guardringfree structure.The fabricated APD experiment results show that it can obtain a very low dark current while achieving a high gain×bandwidth(GB)product.The dark current is 3 nA at 0.9Vb r,and the unit responsivity is 0.4 A/W.The maximum3 dB bandwidth of 24 GHz and a GB product of 360 GHz are achieved for the fabricated APD operating at 1.55μm.

Investigation of Ga_(2)O_(3)/diamond heterostructure solar-blind avalanche photodiode via TCAD simulation

A Ga_(2)O_(3)/diamond separate absorption and multiplication avalanche photodiode(SAM-APD)with mesa structure has been proposed and simulated.The simulation is based on an optimized Ga_(2)O_(3)/diamond heterostructure TCAD physical model,which is revised by repeated comparison with the experimental data from the literature.Since both Ga_(2)O_(3)and diamond are ultra-wide bandgap semiconductor materials,the Ga_(2)O_(3)/diamond SAM-APD shows good solar-blind detection ability,and the corresponding cutoff wavelength is about 263 nm.The doping distribution and the electric field distribution of the SAM-APD are discussed,and the simulation results show that the gain of the designed device can reach 5×10^(4)and the peak responsivity can reach a value as high as 78 A/W.

Recent progress of SiC UV single photon counting avalanche photodiodes

4H-SiC single photon counting avalanche photodiodes(SPADs)are prior devices for weak ultraviolet(UV)signal detection with the advantages of small size,low leakage current,high avalanche multiplication gain,and high quantum efficiency,which benefit from the large bandgap energy,high carrier drift velocity and excellent physical stability of 4 H-SiC semiconductor material.UV detectors are widely used in many key applications,such as missile plume detection,corona discharge,UV astronomy,and biological and chemical agent detection.In this paper,we will describe basic concepts and review recent results on device design,process development,and basic characterizations of 4 H-SiC avalanche photodiodes.Several promising device structures and uniformity of avalanche multiplication are discussed,which are important for achieving high performance of 4 HSiC UV SPADs.

Effects of high-energy proton irradiation on separate absorption and multiplication GaN avalanche photodiode

The effect of high-energy proton irradiation on GaN-based ultraviolet avalanche photodiodes(APDs) is investigated. The dark current of the GaN APD is calculated as a function of the proton energy and proton fluences. By considering the diffusion, generation–recombination, local hopping conductivity, band-to-band tunneling, and trap-assisted tunneling currents, we found that the dark current increases as the proton fluence increases, but decreases with increasing proton energy.

Avalanche photodiodes on silicon photonics

Silicon photonics technology has drawn significant interest due to its potential for compact and high-performance photonic integrated circuits.The Ge-or III-V material-based avalanche photodiodes integrated on silicon photonics provide ideal high sensitivity optical receivers for telecommunication wavelengths.Herein,the last advances of monolithic and hetero-geneous avalanche photodiodes on silicon are reviewed,including different device structures and semiconductor systems.

Short-wavelength infrared InAs/GaSb superlattice hole avalanche photodiode

We demonstrate two short-wavelength infrared avalanche photodiodes based on InAs/GaSb superlattice grown by metal-organic chemical vapor deposition.The difference between the two devices,namely,p+n-n+and p+nn-n+,is that the p+nn-n+device possesses an additional middle-doped layer to separate the multiplication region from the absorption region.By properly controlling the electric field distribution in the p+nn-n+device,an electric field of 906 kV/cm has been achieved,which is 2.6 times higher than that in the p+n-n+device.At a reverse bias of-0.1 V at 77 K,both devices show a 100%cut-off wavelength of 2.25μm.The p+n-n+and p+nn-n+show a dark current density of 1.5×10^-7 A/cm^2 and 1.8×10^-8 A/cm^2,and a peak responsivity about 0.35 A/W and 0.40 A/W at 1.5μm,respectively.A maximum multiplication gain of 55 is achieved in the p+nn-n+device while the value is only less than 2 in the p+n-n+device.Exponential nature of the gain characteristic as a function of reverse bias confirms a single carrier hole dominated impact ionization.

Performance improvement of 4H-SiC PIN ultraviolet avalanche photodiodes with different intrinsic layer thicknesses

Four 4H-SiCp-i-n ultraviolet(UV) avalanche photodiode(APD) samples PIN-0.1, PIN-0.35, PIN-0.5, and PIN-1.0 with different intrinsic layer thicknesses(0.1 μm, 0.35 μm, 0.5 μm, and 1.0 μm, respectively) are designed and fabricated.Single photon detection efficiency(SPDE) performance becomes better as the intrinsic layer thickness increases, which is attributed to the inhibitation of tunneling.Dark count origin is also investigated, an activation energy as small as 0.22 eV of the dark count rate(DCR) confirms that the trap-assisted tunneling(TAT) process is the main source of DCR.The temperature coefficient ranges from-2.6 mV/℃ to 18.3 mV/℃, demonstrating that the TAT process is dominant in APDs with thinner intrinsic layers.Additionally, the room temperature maximum quantum efficiency at 280 nm differs from 48% to 65% for PIN-0.35, PIN-0.5, and PIN-1.0 under 0 V bias, and UV/visible rejection ratios higher than 104 are obtained.

High-Gain N-Face AlGaN Solar-Blind Avalanche Photodiodes Using a Heterostructure as Separate Absorption and Multiplication Regions

It is well known that Ⅲ-nitride semiconductors can generate the magnitude of MV/cm polarization electric field which is comparable with their ionization electric fields. To take full advantage of the polarization electric field, we design an N-face AlGaN solar-blind avalanche photodiode(APD) with an Al_(0.45)Ga_(0.55)N/Al_(0.3)Ga_(0.7)N heterostructure as separate absorption and multiplication(SAM) regions. The simulation results show that the N-face APDs are more beneficial to improving the avalanche gain and reducing the avalanche breakdown voltage compared with the Ga-face APDs due to the effect of the polarization electric field. Furthermore, the Al_(0.45)Ga_(0.55)N/Al_(0.3)Ga_(0.7)N heterostructure SAM regions used in APDs instead of homogeneous Al_(0.45)Ga_(0.55)N SAM structure can increase significantly avalanche gain because of the increased hole ionization coefficient by using the relatively low Al-content AlGaN in the multiplication region. Meanwhile, a quarter-wave AlGaN/AIN distributed Bragg reflector structure at the bottom of the device is designed to remain a solar-blind characteristic of the heterostructure SAM-APDs.

Theoretical analysis for AlGaN avalanche photodiodes with mesa and field plate structure

To suppress the electric field crowding at sidewall and improve the detection sensitivity of the AlGaN separate absorption and multiplication(SAM)avalanche photodiodes(APDs),we propose the new AlGaN APDs structure combining a large-area mesa with a field plate(FP).The simulated results show that the proposed AlGaN APDs exhibit a significant increase in avalanche gain,about two orders of magnitude,compared to their counterparts without FP structure,which is attributed to the suppression of electric field crowding at sidewall of multiplication layer and the reduction of the maximum electric field at the p-type GaN sidewall in p-n depletion region.Meanwhile,the APDs can produce an obviously enhanced photocurrent due to the increase in cross sectional area of multiplication region.

Bias-dependent timing jitter of 1-GHz sinusoidally gated InGaAs/InP avalanche photodiode

We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage(V_(ex)) when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diode was cooled to-30 degrees Celsius.When the V_(ex) is too low(0.2 V-0.8 V) or too high(3 V-4.2 V),the timing jitter is increased with the V_(ex),particularly at high V_(ex).While at middle V_(ex)(1 V-2.8 V),the timing jitter is reduced.Measurements of the timing jitter of the same avalanche diode with pulsed gating show that this effect is likely related to the increase of both the amplitude of the V_(ex) and the width of the gate-on time.For the 1-GHz sinusoidally gated detector,the best jitter of 93 ps is achieved with a photon detection efficiency of 21.4%and a dark count rate of ~2.08×10^(-5) per gate at the V_(ex) of 2.8 V.To evaluate the whole performance of the detector,we calculated the noise equivalent power(NEP) and the afterpulse probability(P_(ap)).It is found that both NEP and P_(ap) increase quickly when the V_(ex) is above 2.8 V.At ~2.8-V V_(ex),the NEP and P_(ap) are ~2.06×10^(16)W/Hz^(1/2) and 7.11%,respectively.Therefore,the detector should be operated with V_(ex) of 2.8 V to exploit the fast time response,low NEP and low P_(ap).

A Double Heterostructure Multiplication Region in AlGaN Based SAGCM Avalanche Photodiode

In this study, separate absorption, grading, charge, and multiplication (SAGCM) avalanche photodiode (APD) with double heterojunction AlN/AlxGa1-xN/GaN in multiplication region were designed to reduce excess noise using Monte Carlo simulation. The multiplication region was broken to three different regions and tried to enhance localization of the first and second impact ionization events at near the heterojunctions. The excess noise of the proposed structure, for high gains, was 64% smaller than that of the fabricated standard AlGaN-APDs.

Noise Temperature Characteristics and Gain-control of Avalanche Photodiodes for Laser Radar

Avalanche photodiodes(APDs) are promising light sensors with high quantum efficiency and low noise. It has been extensively used in radiation detection,laser radar and other weak signal detection fields. Unlike other photodiodes,APD is a very sensitive light detector with very high internal gain. The basic theory shows that the gain of APD is related to the temperature. The internal gain fluctuates with the variation of temperature. Investigated was the influence of the variation of the gain induced by the fluctuation of temperature on the output from APD for a very weak laser pulse input in laser radar. An active reverse-biased voltage compensation method is used to stabilize the gain of APD. An APD model is setup to simulate the detection of light pulse signal. The avalanche process,various noises and temperature's effect are all included in the model. Our results show that for the detection of weak light signal such as in laser radar,even a very small fluctuation of temperature could cause a great effect on APD's gain. The results show that the signal-to-noise ratio of the APD's output could be improved effectively with the active gain-control system.

Zener Phenomena in InGaAs/InAlAs/InP Avalanche Photodiodes

Avalanche photodiodes are widely utilized in research, military and commercial applications which make them attractive for further development. In this paper the results of numerical simulations of uncooled InGaAs/InAlAs/InP based photodiodes are presented. The devices were optimized for 1.55 μm wavelength detection. For device modeling the APSYS Crosslight software was used. Simulated structure consists of separate absorption, charge and multiplication layers with undepleted absorption region and thin charge layer. Based on numerical calculations, the device characteristics like band diagram, dark current, photo current, gain, breakdown voltage and gain bandwidth product were evaluated. The simulation results highlight importance of Zener effect in avalanche photodiode operation.

APD阵列及其成像激光雷达系统的研究进展

激光雷达(LiDAR)广泛应用于航天器导航、安防监控、3-D测绘、自动驾驶汽车、军事装备及机器人等领域,具有重要的军事和民用价值。雪崩光电二极管(APD)阵列探测技术在LiDAR的发展过程中发挥着至关重要的作用。介绍了LiDAR和APD阵列的应用背景,综述了APD阵列和LiDAR系统的发展历程和最新进展,最后总结了APD阵列探测技术的发展前景和研究趋势。

考虑APD的部分相干光OFDM-UWOC系统性能

对于实际的水下无线光通信系统,系统误码性能主要受到海洋湍流和接收机噪声的制约。考虑散粒噪声和热噪声的影响,对弱海洋湍流环境下基于雪崩光电二极管的部分相干光辅助OFDM-UWOC系统的误码性能进行了分析。研究中利用波束扩展函数建立了吸收、散射、未对准和海洋湍流共同影响下的聚合信道衰落模型,进而分别导出不同噪声限制下的系统平均误码率理论表达式。受散粒噪声限制时,研究了接收机噪声温度、平均接收光强及雪崩光电二极管雪崩增益值的大小对系统可靠性的影响;受热噪声限制时,给出了部分相干光特征参数和海洋湍流特性参数对该系统可靠性的影响。结果表明,对于雪崩光电二极管而言,接收机温度和平均接收光强大小都会在一定程度上影响系统误码性能。因此,通过选择合适的雪崩光电二极管雪崩增益值,能够在一定程度上提升该OFDM-UWOC系统的误码性能。此外,部分相干光和海洋湍流的变化会对系统的误码性能产生影响。

基于机器学习的复杂环境下APD最优偏置电压补偿方法

雪崩光电二极管(APD)在激光雷达探测系统中的信噪比受工作距离和背景辐射的影响较大,传统探测方法通过离线式或事先根据外界环境影响因素进行预补偿,不能在线动态调节,难以适应复杂环境。一种基于机器学习的APD偏置电压最佳补偿方法,可以准确判断APD当前的工作状态,对偏置电压进行二分补偿,使APD工作在最优状态。通过比较多种机器学习模型,选用准确率维持在98%以上的随机森林算法来判断APD工作状态。在不同距离下测试,该方法可保证偏置电压始终处于最优工作电压下,提高激光雷达探测系统的性能。

High-uniformity 2×64 silicon avalanche photodiode arrays with silicon multiple epitaxy technology

In this paper,high-uniformity 2×64 silicon avalanche photodiode[APD]arrays are reported.Silicon multiple epitaxy technology was used,and the high performance APD arrays based on double-layer epiwafers are achieved for the first time,to the best of our knowledge.A high-uniformity breakdown voltage with a fluctuation of smaller than 3.5 V is obtained for the fabricated APD arrays.The dark currents are below 90 pA for all 128 pixels at unity gain voltage.The pixels in the APD arrays show a gain factor of larger than 300 and a peak responsivity of 0.53 A/W@M=1 at 850 nm[corresponding to maximum external quantum efficiency of 81%]at room temperature.Quick optical pulse response time was measured,and a corresponding cutoff frequency up to 100 MHz was obtained.