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Effect of amino-, mercapto-silane coupling as a molecular bridge of polyvinyl chloride ion-selective membrane on silicon nitride for nitrate ISFET sensors
(2020-06-01)
Chaisriratanakul, Woraphan
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Bunjongpru, Win
;
Pankiew, Apirak
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Srisuwan, Awirut
;
Jeamsaksiri, Wutthinan
This paper presents a modification of a Si<inf>3</inf>N<inf>4</inf> Polyvinyl chloride (PVC) membrane on a surface of an ion selective field effect transistor (ISFET) using silane with two different functional groups for comparison of nitrate sensing characteristics. Effects of amino (NH<inf>2</inf>) and thiol groups (SH) toward structures and characteristics of nitrate sensors were analyzed using the following techniques: ellipsometry, scanning electron microscope (SEM), infrared spectroscopy (FTIR), zeta potential and electrochemical impedance spectroscopy (EIS). After surface modification, the thickness of the silane layers for both cases were similar with uniform surface topology. Absolute zeta potentials of PVC ion-selective membrane (7.65 mV) and Si<inf>3</inf>N<inf>4</inf> surface modification with MPTMS (-51.46 mV) reflected the surface functional group and showed that membranes could be bonded to the PVC ion-selective membrane. Since APTMS produced higher EIS than MPTMS, the resulting nitrate sensors modified by MPTMS had higher sensitivity than the sensors with APTMS. Finally, the modified sensors had a useful life time of 3 months.
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Modification of polyvinyl chloride ion-selective membrane for nitrate ISFET sensors
(2020-05-15)
Chaisrirattanakua, Woraphan
;
Bunjongpru, Win
;
Pankiew, Apirak
;
Srisuwan, Awirut
;
Jeamsaksiri, Wutthinan
In this work, a Polyvinyl Chloride (PVC) ion-selective membrane was modified to detect nitrate based on Ion Selective Field Effect Transistor (ISFET) sensing technology in order to eliminate chloride interference. A modification was done with ethylenediamine solution to achieve animated PVC, which was then oxidized with sodium tungstate to form nitrone coated PVC membrane. The modified PVC was characterized using FTIR, 1H NMR, GPC, FE-SEM and EIS. The FTIR spectrum of animate PVC demonstrated -NH<inf>2</inf> bending at 1580 cm−1, NO<inf>2</inf> asymmetric stretching at 1650 cm−1 and N[sbnd]O out-of-plane deformation vibration at 837 cm−1. GPC analysis of the modified PVC showed that the PVC molecular weight was shifted to a high molecular weight. The PVC ion-selective membrane was immobilized on the ISFET to create nitrate sensors with the following characteristics. The Nitrate-Nitrogen detection limit is 1.20 ppm with linear range from 3−20 ppm at sensitivity of 56 ± 2 mV/dec. The sensor is useful for detecting small amount of nitrate in a mixed solution, which usually is the case in most situations. This sensor could be applied in many applications, such as agricultural industry, water reserve management and medical field as well.
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The study of p-n and schottky junction for magnetodiode
(2012-01-01)
Phetchakul, Toempong
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Luanatikomkul, Wittaya
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Leepattarapongpan, Chana
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Chaowicharat, Ekalak
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Pengpad, Putapon
This paper presents the simulation model of Dual Magnetodiode and Dual Schottky Magnetodiode using Sentaurus TCAD to simulate the virtual structure of magneto device and apply Hall Effect to measure magnetic field response of the device. Firstly, we use the program to simulate the magnetodiode with p-type semiconductor and aluminum anode and measure electrical properties and magnetic field sensitivity. Simulation results show that sensitivity of Dual Schottky magnetodiode is higher than that of Dual magnetodiode.
2
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The deflection length and emitter width on sensitivity of magnetotransistor
(2011-10-04)
Phetchakul, Toempong
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Sottip, Panyakorn
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Leepattarapongpan, Chana
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Penpondee, Narichapan
;
Pengpad, Putapon
This paper presents a study of effect of deflection length and emitter width on sensitivity of magnetotransistor. The device has been fabrication on standard CMOS technology. It can detect magnetic field applied vertically to the chip. The structure consists of emitter (n-type), base (p-type) and collector (n-type) on silicon p-substrate. The device can sense magnetic field by Hall Effect theory and carrier deflection resulting to difference between base and collector current (ΔI<inf>CB</inf>) related to magnetic field (B <inf>Z</inf>) strength. From the experiment is comparing emitter width of 4, 5 and 10 micrometer at deflection length of 10 and 20 micrometer. The result shows that increase in injection emitter width cause to the sensitivity decreases and the deflection length of 20 micrometer is the best sensitivity. These results are very useful for developing the magnetotransistor for high sensitivity and performance. © 2011 IEEE.
1
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Fabrication, characterization and analysis of ITO/n-Si Schottky photodetector
(2010-07-30)
Ueamanapong, Surada
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Srithanachai, Itsara
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Atiwongsangthong, Narin
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Pengpad, Putapon
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Niemcharoen, Surasak
In this article, we have studied contact between indium tin oxide (ITO) and n-type silicon. First, the characteristics of ITO thin films have been identified. The films have high transparent and low resistivity (∼88 % of transmittance and 2.8×10-3 Ω-cm). Fabrication of the ITO/n-Si photodetector was presented which was ITO thin layer deposited on 10 Ω-cm resistivity silicon wafer by R.F. sputter method. Finally, a study of characteristics of the photodetector such as I-V characteristics, C-V characteristics, and frequency response has been done. The photodetectors have built in voltage (V<inf>bi</inf>) about 0.26 V, the dark current of 5 μA and light current of 1.5 mA at 25,000 lux, 5V. Capacitance and frequency response are about 110 pF and 120 kHz, respectively.
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The low power magnetotransistor based on the CMOS technology
(2010-07-30)
Sottip, Panyakorn
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Phetchakul, Toempong
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Leepattarapongpan, Chana
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Penpondee, Naritchapan
;
Pengpad, Putapon
This paper presents the low power magnetotransistor detect magnetic field density in vertical direction. The devices can detect magnetic field by Lorentz force act upon minority carrier in base and difference between base and collector current (ΔI<inf>CB</inf>) was occurred. The structure of the low power magnetotransistor consist of one emitter, one collector and one base contact and designed decrease emitter injection area was 5 um and growth LOCOS oxide around emitter area. The structure was generated and simulated by TCAD Sentuarus simulation package and shows increase sensitivity of the low power magnetotransistor when compare the three terminals magneto-transistor. From the experiment, the low power magneto-transistor can operate at bias current less than 1 mA and high sensitivity is 20.64 mV/T. The device increase sensitivity 2.53 times at bias current 5 mA and decrease power consumption 85% when compare the three terminals magnetotransistor.
2
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Generation lifetime analysis of p-n junction x-ray detector
(2010-07-30)
Rujanapich, Poopol
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Poyai, Amporn
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Srithanachai, Itsara
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Pengpad, Putapon
;
Hruanan, Charndet
Operation lifetime of the X-ray detector is the major factor that defines cost of detector or the actual operation cost of the detector. The purpose of this paper is to study the possibility of operation lifetime extension of the silicon x-ray detector. The study of the device's carrier generation lifetime before and after device exposed to the X-ray for 4 and 150 second at 40, 55 as well as 70 keV were conducted in this paper. The 1 mm2 p-n junctions were fabricated by boron implantation process into phosphorus doped silicon wafer. A commercial x-ray source for dentist was used to generate x-ray in these experiments. The carrier generation lifetime was calculated from current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The results show that the carrier generation lifetime increased after 4 second of x-ray irradiation at all three energy conditions but decreased back close to the original value after continue exposed devices for another 150 second. However, the lowest point of the generation lifetime after 4 second of x-ray irradiation is depending on the level of energy used. The results also presented that the defects that caused by x-ray irradiation are manageable.

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