• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.99-101
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• 2000

The fabrication of the submicron size hole has been interesting due to the potential application of the near field optical sensor or liquid metal ion source. The 2 micron size dot array was photolithographically patterned. After formation of the V-groove shape by anisotropic KOH etching, dry oxidation at $1000^{\circ}C$ for 600 minutes was followed. In this procedure, the orientation dependent oxide growth was performed to have an etch-mask for dry etching. The reactive ion etching by the inductively coupled plasma (ICP) system was performed in order to etch ~90 nm $SiO_2$ layer at the bottom of the V-groove and to etch the Si at the bottom. The negative ion energy would enhance the anisotropic etching by the $Cl_2$ gas. After etching, the remaining thickness of the oxide on the Si(111) surface was measured to be ~130 nm by scanning electron microscopy. The etched Si aperture can be used for NSOM sensor.

• Journal of Sensor Science and Technology
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• v.30 no.1
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• pp.51-55
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• 2021

We demonstrated a polymer dielectric with low leakage characteristics through an optimal blade coating method for low-cost and large-scale fabrication of metal-insulator-metal (MIM) capacitors. Cross-linked poly(4-vinylphenol) (C-PVP), which is a typically used polymer dielectric, was coated on a 10 × 10 cm indium-tin-oxide (ITO) deposited glass substrate by changing the deposition temperature (TD) and coating velocity (VC) in the blade coating. During the blade coating, the thickness of the thin c-PVP varied depending on TD and VC owing to the 'Landau-Levich (LL) regime'. The c-PVP-dielectric-based MIM capacitor fabricated in this study showed the lowest leakage current characteristics (10-6 A/㎠ at 1.2 MV/㎠, annealing at 200 ℃) and uniform electrical characteristics when TD was 30 ℃ and VC was 5 mm/s. In addition, at TD = 30 ℃, stable leakage characteristics were confirmed when a different electric field was applied. These results are expected to positively contribute to applications with next-generation electronic devices.

• Journal of Sensor Science and Technology
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• v.15 no.2
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• pp.102-105
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• 2006

In-vivo dosimetry is an essential tool of quality assurance programs in radiotherapy. The most commonly used techniques to verify dose are thermoluminescence dosimeter (TLD) and diode detectors. Metal oxide semiconductor field-effect transistor (MOSFET) has been recently proposed for using in radiation therapy with many advantages. The reproducibility, linearity, isotropy, dose rate dependence of the MOSFET dosimeter were studied and its availability was verified. Consequently the results can be used to improve therapeutic planning procedure and minimize treatment errors in radiotherapy.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.11-16
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• 2007

CuO is an important transition metal oxide with many practical applications such as catalysts, p-type semiconductor, solar cells, magnetic storage media and cathode materials. In this contribution, nanocrystalline CuO powders were prepared by solution reduction method using copper chloride ($CuCl_{2}{\cdot}2H_{2}O$), hydrazine ($N_{2}H_{4}$) and NaOH and subsequent heat treatment. The gas sensor using nanocrystalline CuO powders showed high sensitivities to acetone and ethanol.

• Journal of Sensor Science and Technology
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• v.20 no.5
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• pp.294-299
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• 2011

$SnO_2$ nanoparticles were synthesized by a hydrothermal method and gas sensors were fabricated using nanoparticles to detect dimethyl methylphosphonate(DMMP) gas. The prepared $SnO_2$ nanoparticles exhibited a high response(72 at $500^{\circ}C$) to 5 ppm DMMP gas compared to commercial $SnO_2$ nanopowders, but their recovery was relatively poor. Various metals(Ni, Sb, Nb) were added to the $SnO_2$ nanoparticles to improve their recovery properties. The focus of this study was to investigate the effects of metal oxide additives on DMMP sensing behavior in $SnO_2$ nanoparticles.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.159-159
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• 2017

• Journal of Sensor Science and Technology
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• v.33 no.1
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• pp.12-17
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• 2024

Floating inverter amplifiers (FIAs) have recently garnered considerable attention owing to their high energy efficiency and inherent resilience to input common-mode voltages and process-voltage-temperature variations. Since the voltage gain of a simple FIA is low, it is typically cascaded or cascoded to achieve a higher voltage gain. However, cascading poses stability concerns in closed-loop applications, while cascoding limits the output swing. This study introduces a gain-enhanced FIA that features cross-coupled body biasing. Through simulations, it is demonstrated that the proposed FIA designed using a 28-nm complementary metal-oxide-semiconductor technology with a 1-V power supply can achieve a high voltage gain (> 90 dB) suitable for dynamic open-loop applications. The proposed FIA can also be used as a closed-loop amplifier by adjusting the amount of positive feedback due to the cross-coupled body biasing. The capability of achieving a high gain with minimum-length devices makes the proposed FIA a promising candidate for low-power, high-speed sensor interface systems.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.407-412
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• 2007

For $VO_{2}$ sensors applicable to temperature measurement by using the nature of semiconductor to metal transition, the crystallinity, microstructure, and temperature vs. resistance characteristics were investigated systematically as a function of the annealing condition. The starting materials, vanadium pentoxide ($V_{2}O_{5}$) powders, were mixed with vehicle to form paste. This paste was screen-printed on $Al_{2}O_{3}$ substrates and then $VO_{2}$ thick films were heat-treated at $450^{\circ}C$ to $600^{\circ}C$, respectively, for 1 hr in $N_{2}$ gas atmosphere for the reduction. As results of the temperature vs. resistance property measurements, the electrical resistance of the $V_{2}O_{5}$ sensor in phase transition range was decreased by $10^{3.9}$ order. The presented critical temperature sensor could be used in fire-protection and control systems.

• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.357-361
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• 2018

This paper presents an averaging current adjustment technique for reducing the pixel resistance variation in a bolometer-type uncooled infrared image sensor. Each unit pixel was composed of an active pixel, a reference pixel for the averaging current adjustment technique, and a calibration circuit. The reference pixel was integrated with a polysilicon resistor using a standard complementary metal-oxide-semiconductor (CMOS) process, and the active pixel was applied from outside of the chip. The averaging current adjustment technique was designed by using the reference pixel. The entire circuit was implemented on a chip that was composed of a reference pixel array for the averaging current adjustment technique, a calibration circuit, and readout circuits. The proposed reference pixel array for the averaging current adjustment technique, calibration circuit, and readout circuit were designed and fabricated by a $0.35-{\mu}m$ standard CMOS process.

• Current Optics and Photonics
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• v.7 no.5
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• pp.485-495
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• 2023

The pixel size in high-resolution complementary metal-oxide-semiconductor (CMOS) image sensors continues to shrink due to chip size limitations. However, the pixel pitch's miniaturization causes deterioration of optical performance. As one solution, a quad color filter (CF) array with pixel binning has been developed to enhance sensitivity. For high sensitivity, the microlens structure also needs to be optimized as the CF arrays change. In this paper, the covered microlens, which consist of four microlenses covered by one large microlens, are proposed for the quad CF array in the backside illumination pixel structure. To evaluate the optical performance, the suggested microlens structure was simulated from 0.5 ㎛ to 1.0 ㎛ pixels at the center and edge of the sensors. Moreover, all pixel structures were compared with and without in-pixel deep trench isolation (DTI), which works to distribute incident light uniformly into each photodiode. The suggested structure was evaluated with an optical simulation using the finite-difference time-domain method for numerical analysis of the optical characteristics. Compared to the conventional microlens, the suggested microlens show 29.1% and 33.9% maximum enhancement of sensitivity at the center and edge of the sensor, respectively. Therefore, the covered microlens demonstrated the highly sensitive image sensor with a quad CF array.