• Current Optics and Photonics
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• v.3 no.6
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• pp.510-515
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• 2019

In this paper, we introduce a 1.3-㎛ 25-GHz waveguide-integrated vertical PIN type Ge-on-Si photodetector fabricated using a multi-project wafers service based on fringing field analysis in the depletion region. In general, 1.3-㎛ photodetectors fabricated using a commercial foundry service can achieve limited bandwidths because a significant amount of photo-generated carriers are located within a few microns from the input along the device length, and they are influenced by the fringing field, leading to a longer transit time. To estimate the response time, we calculate the fringing field in that region and the transit time using the drift velocity caused by the field. Finally, we compare the estimated value with the measured one. The photodetector fabricated has a bandwidth of 20.75 GHz at -1 V with an estimation error of <3 GHz and dark current and responsivity of 110 nA and 0.704 A/W, respectively.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.387-394
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• 2005

In order to design SOI CMOS image sensors, SOI MOSFET model parameters were extracted using the equation of bulk MOSFET model parameters and were optimized using SPICE level 2. Simulated I-V characteristics of the SOI NMOSFET using the extracted model parameters were compared to the experimental I-V characteristics of the fabricated SOI NMOSFET. The simulation results agreed well with experimental results. A unit pixel for SOI CMOS image sensors was designed and was simulated for the PPS, APS, and logarithmic circuit using the extracted model parameters. In these CMOS image sensors, a nano-wire MOSFET photodetector was used. The output voltage levels of the PPS and APS are well-defined as the photocurrent varied. It is confirmed that SOI CMOS image sensors are faster than bulk CMOS image sensors.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.257-261
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• 2015

We report on GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) that can cover the spectral range of $3.6-25{\mu}m$. One advantage of the GaAs QWIPs is the wavelength tenability as a function of their structural parameters. We have performed a systematic calculation on the detection wavelength of a typical $GaAs/Al_xGa_{1-x}As$ multi-quantum-well photodetector, with the aluminum mole fraction (x) of $Al_xGa_{1-x}As$ barrier in the range of 0.15-0.43 and the quantum-well width range from 30 to 60 $60{\AA}$. Design and fabrication of a QWIP based on $GaAs/Al_{0.23}Ga_{0.77}As$ structure with $37{\AA}$-thick well width has been carried out. The calculated operation wavelength of the QWIP is in a good agreement with the experimental data taken by photo response and activation energy calculation from thermal quenching of integrated photoluminescence.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.323-324
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• 2007

Investigation of improving the properties of UV photodetector which uses the wide bandgap of ZnO are under active progress. In this paper, transparent conducting aluminum-doped Zinc oxide films(AZO) were prepared by rf magnetron sputtering on glass(corning 1737) and p-Si substrate, were then annealed at temperature $400^{\circ}C$ for 2hr. The AZO thin films were deposited by RF sputtering system. HF power and work pressure is 120 W and 15 mTorr, respectively, and the purity of AZO target is 5N. The AZO thin films were deposited at 300, 400, $500^{\circ}C$, and $600^{\circ}C$. For sample deposited at $400^{\circ}C$, we observed best $V_r-I_{ph}$ of 0.94 mA and good transmittance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.370-371
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• 2007

To investigate the ZnO thin films which are interested in the next generation of short wavelength LEDs and Lasers and UV photodetector with p-type inversion layer, the ZnO thin films were deposited by. RF sputtering system. Substrate temperature and work pressure is $100^{\circ}C$ and 15 mTorr, respectively, and the purity of ZnO target is 5N. The ZnO thin films were deposited at $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, and $400^{\circ}C$. For sample deposited at $300^{\circ}C$, we observed full width at half maximum (FWHM) of 0.240 and good surface morphology.

• Electrical & Electronic Materials
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• v.17 no.2
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• pp.14-19
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• 2004

• Journal of Sensor Science and Technology
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• v.25 no.4
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• pp.252-256
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• 2016

Epitaxially grown GaN layers have a high surface state density, which typically results in a surface leakage current and a photoresponse in undesirable wavelengths in GaN optoelectronic devices. Surface passivation is, therefore, an important process necessary to prevent performance degradation of GaN UV photodetectors. In this study, we propose oxygen-enhanced thermal treatment as a simple surface passivation process without capping layers. The GaN UV photodetector fabricated using a thermal annealing process exhibits improved electrical and photoresponsive characteristics such as a reduced dark current and an enhanced photoresponsive current and UV-to-visible rejection ratio. The results of this study show that the proposed surface passivation method would be useful to enhance the reliability of GaN-based optoelectronic devices.

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.308-314
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• 1999

We used the photoreflectance spectroscopy for characterization of the infrared photodetector structure we GaAs/$Al_{0.3}Ga_{0.7}As$ multi-quantum well (MQW) structures grown by molecular beam epitaxy (MBE) method. Energy gap related transitions in GaAS and AlGaAs were observed. The Al composition(x) was determined b Sek's composition formula. MQW related transition energies were identify the transitions, the experimentally observed energies were compare with results of the envelope function approximation for a rectangular quantum well.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.40-40
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• 2010

CdSe nanocrystals (NCs) have been decorated on singlewalled carbon nanotubes (SWCNTs) by combining a method of chemically modified substrate along with gate-bias control. CdSe/ZnS core/shell quantum dots were negatively charged by adding mercaptoacetic acid (MAA). The silicon oxide substrate was decorated by octadecyltrichlorosilane (OTS) and converted to hydrophobic surface. The negatively charged CdSe NCs were adsorbed on the SWCNT surface by applying the negative gate bias. The selective adsorption of CdSe quantum dots on SWCNTs was confirmed by confocal laser scanning microscope. The measured photocurrent clearly demonstrates that CdSe NCs decorated SWCNT can be used for photodetector and solar cell that are operable over a wide range of wavelengths.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1073-1076
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• 2003

This paper shows the performance as a photodetector of InP/InGaAs HPT operated with a base bias and forntside optical injection through the emitter. InP/InGaAs HPT produced the high optical gain of about 16.2 where HPT is biased at Vc=1V, I$_{B}$=20$\mu$A with an input optical power of 2.4$\mu$W. And we examined that the optical gain of HPTs becomes larger when operating in 3-terminal configuration rather than 2-terminal with the floating base. The optical performance of InP/InGaAs HPT is an attractive to the PIN Photodetector for use in long wavelength optical receivers.s.