• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1667-1671
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• 2024

This paper presents a neutron/gamma detector based on a micropixel avalanche photodiode and a plastic scintillator that monitors the status of the accelerator-driven intense resonance neutron source (IREN) facility by measuring the neutron/gamma intensity in the target hall. The electronics of the neutron/gamma detector has been designed and developed. The size of the plastic scintillator was selected to be 3.7 × 3.7 × 30 mm³ due to the sensitive area of the MAPD. The experimental results demonstrated a dependence between the count rate of the detector and the frequency of the accelerator. The detector is sensitive to intermediate and fast neutrons. The minimum detectable energy was determined to be 200 keV using Cs-137 point gamma source. The maximum counting rate of the detector from TTL out is about 2.2⋅10⁶ counts/sec, but for analogue output it is about 2⋅10⁷ counts/sec. The detector can not allow discriminating neutrons and gamma rays by charge integration method.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.43-49
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• 1997

The dependence of the electrical properties in planar MQW - APD & pn, and p - i - n photodiode implanted with oxygen on the annealing emperatures and ion dose has been investigated. The oxygen implantation was performed for inter-device isolation. The leakage current of as-impanted p-i-n photodiode obtained was less than 50 nA. An annelaing temperature dependence study shows an abrupt increase of leakge current at 600.deg.C for all devices under study. This indicates that donor complex centers introduced by the chemical activity of oxygen increase with increasing annelaing temperatures. Furthermore, leakage current was highly correlated with oxygen dose due to th eimplanted related defects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.206-209
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• 2002

With the progress of semiconductor processing technology, avalanohe photodiodes (APDs) based on InP/InGaAs are used for high-speed optical receiver modules. Planar-type APDs give higher reliability than mesa-type APDs. However, Planar-type APDs are struggled with a problem of intensed electric field at the junction curvature, which causes edge breakdown phenomena at the junction periphery. In this paper, we focused on studying the effects of junction curvature for APDs performances by different etching processes followed by single diffusion to from p-n junction. The performance of each process is characterized by observing electric field profiles and carrier generation rates. From the results, it can be understood to predict the optimum structure, which can minimize edge breakdown and improve the manufacturability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.241-245
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• 2001

In this paper, we present parameter optimization technique for GaAs/AlGaAs multiple quantum well avalanche photodiodes used for image capture mechanism in high-definition system. Even under flawless environment in semiconductor manufacturing process, random variation in process parameters can bring the fluctuation to device performance. The precise modeling for this variation is thus required for accurate prediction of device performance. The precise modeling for this variation is thus required for accurate prediction of device performance. This paper will first use experimental design and neural networks to model the nonlinear relationship between device process parameters and device performance parameters. The derived model was then put into genetic algorithms to acquire optimized device process parameters. From the optimized technique, we can predict device performance before high-volume manufacturign, and also increase production efficiency.

• Korean Journal of Optics and Photonics
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• v.24 no.4
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• pp.176-183
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• 2013

In this paper, we report the design, fabrication and characterization of the 3-Dimensional optical receiver for a Laser Detection And Ranging (LADAR) system. The optical receiver is composed of three parts; $16{\pm}16$ Geiger Mode InGaAs Avalanche Photodiode (APD) array device operated at 1560 nm wavelength, Read Out Integrated Circuit (ROIC) measuring the Time-Of-Flight (TOF) of the return signal reflected from target objects, a package and cooler maintaining the proper operational condition of the detector and control electronics. We can confirm that the LADAR system can detect the signal from a target up to 1.2 km away, and it showed low Dark Count Rate (DCR) of less than 140 kHz, and higher than 28%-Photon Detection Efficiency (PDE). This is considered to be the best performance of the $16{\pm}16$ FPA APD optical receiver for a LADAR system.

• KIEE International Transactions on Electrophysics and Applications
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• v.2C no.5
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• pp.273-278
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• 2002

Even though the modulating signal frequency of the light is too high to detect directly, the signal can be extracted by frequency conversion at the same time as the detection by means of the non-linearity of the APD. An analysis is presented for super-high-speed optical demodulation by an APD with electronic mixing. A normalized gain is defined to evaluate the performance of the frequency conversion demodulation. The nonlinear effect of the internal capacitance was included in the small signal circuit analysis. We showed theoretically and experimentally that the normalized gain is dependent on the down converted difference frequency component. In the experiment, the down converted different frequency outputs became larger than the directly detected original signal for the applied local signal of 20㏈m.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.278-279
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• 2004

The multiplication region of an APD(Avalanche photodiode) plays a critical role in determining the gain, the multiplication noise, and the gain-bandwidth product. we compared and analyzed the local model and the non-local model for a 10Gb/s APD designing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.172-175
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• 2016

Time of Flight(ToF) LiDAR(Light Detection And Ranging) technology has been used for distance measurement and object detection by measuring ToF time information. This technology has been evolved into higher precision measurement field such like autonomous driving car and terrain analysis since the retrieval of exact ToF time information is of prime importance. In this paper, as a accuracy indicator of the ToF time information, timing jitter was measured and analyzed through Single-Shot LiDAR system(SSLs) mainly consisting of 1.5um wavelength MOPA LASER, InGaAs Avalanche Photodiode(APD) at 31M free space environment. Additionally, we applied spline interpolation and multiple-shot averaging method on measured data through SSLs to improve ToF timing information.

• ETRI Journal
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• v.31 no.5
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• pp.622-624
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• 2009

This letter presents a compact 2.5 Gb/s burst-mode receiver using the first reported monolithic amplifier IC developed with 0.25 ${\mu}m$ SiGe BiCMOS technology. With optimum avalanche photodiode gain, the receiver module can obtain a fast response, high sensitivity and wide dynamic range, satisfying the overhead timing and various power specifications for a 2.5 Gb/s next-generation passive optical network (PON), as well as a legacy 1.25 Gb/s PON in the upstream.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.180-180
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• 2004

정밀한 계측의 필요성이 높아지면서 레이저는 그 신뢰성과 사용 편의성으로 인해 거리측정에도 높은 활용을 보이고 있다. 레이저 거리측정기(laser range finder, LRF)의 원리는 20ns 미만의 짧은 레이저 펄스를 표적에 발사한 후 반사되어 돌아오는 신호의 시간과 빛의 속도를 곱하여 거리를 계산하는 방식이다. 이러한 반사펄스(pulse-echo techniques)법은 수m-수백만 km까지의 거리측정에 사용되는 방식으로서 정밀하고 빠른 측정이 가능할 뿐 아니라 단지 목표물을 확인하고 측정버튼을 누름으로써 결과를 얻을 수 있는 사용 편의성을 장점으로 한다.(중략)