Toempong Phetchakul

Magnetotransistor Based on the Carrier Recombination—Deflection Effect

This paper presents the three-terminal magnetotransistor based on the carrier recombination-deflection effect. Three-terminal magnetotransistor can detect vertical and lateral magnetic field direction. The structure of magnetotransistor consists of one emitter, one collector and one base contact. The devices can detect magnetic field by relying on the difference between base current and collector current (¿ICB). The result from experiments closely matched the simulated 3-D modeling with base width of 20 ¿m at substrate thickness of 600 ¿m . From the experiment, the magnetotransistor had the highest sensitivity of 10.25%/T when emitter current was at 10 mA. This research on the three-terminal magnetotransistor can achieve magnetic sensors with small size, high performance and wide range of applications.

Merged three-terminal magnetotransistor based on the carrier recombination - deflection effect

This article presents a merged three terminals magnetotransistor based on the carrier recombination - deflection effect. This particular magnetotransistor structure relies on the combination of difference of base current and collector current in +x and -x directions. As a result, the output voltage and absolute sensitivity to magnetic field will be double. The structure of magnetotransistor consists of one emitter, two collector and two base contacts. The devices can detect magnetic field in vertical direction (BZ) by relying on the difference between base current and collector current (DeltaICB). From the experiment, with emitter current at 5, 8, and 10 mA, the magnetotransistor had the highest sensitivity of 1.125 mV/mT when emitter current was at 10 mA.

A merged magnetotransistor for 3-axis magnetic field measurement based on carrier recombination–deflection effect

Abstract This article presents a novel magnetotransistor based on carrier recombination–deflection effect for detecting magnetic field in three dimensions ( B X , B Y , and B Z ) by relying on the difference between base and collector currents (∆ I CB ). This device used low biasing current. It was designed and fabricated using CMOS fabrication technology. The device structure consisted of one emitter, 4 collectors and 4 bases. All four collector terminals were connected with each other. The same was true for the four base terminals. LOCOS oxide was grown to surround the emitter area to limit lateral carrier loss, and therefore reducing the overall biasing current. The experiment showed that, at 0.2xa0mA of biasing current, the B X , B Y and B −Z direction sensitivity to magnetic field within the range of 0-400xa0mT are 2, 5 and 14.5%/T, respectively. This research on the merged magnetotransistor produced magnetic sensors with small size, high performance with wide range of applications.

Monitoring of Draft Beer Fermentation Process by Electronic Nose

The draft beer fermentation process was monitored by using electronic nose. The system used the seven types of generally commercial metal oxide gas sensor in array. The selected process was one of the commercial processes and the data were gathered every hour for 10 day process which was 240 steps. It was processed for monitoring the chemical reaction for quality control. The results showed the good difference of the chemical reaction of the each day very clearly. The signature processing showed the variance 98.78 %, 96.55 % of the first component (PC1) and 2.3 % of the second component (PC2), which was sufficiency for data explanation in 2D plot. It would be useful for production process to ensure a quality standard.

The low power 3D-magnetotransistor based on CMOS technology

This article presents a 3D magnetotransistor for detecting magnetic field in three dimensions (BX, BY, and BZ) by relying on the difference between base and collector currents (ΔICB). This device used low biasing current. It was designed and fabricated using CMOS fabrication technology. The device structure consisted of one emitter, 4 collectors and 4 bases. LOCOS oxide was grown to surround the emitter area to limit lateral carrier loss, and therefore reducing the overall biasing current. The experiment showed that, at 0.2 mA of biasing current, the BX, BY and BZ direction sensitivity to magnetic field within the range of 0 – 400 mT are 0.05, 0.07 and 0.145 mV/mT, respectively.

The Effect of Anode Width of Dual Schottky Magnetodiode to Sensitivity

This article studies the effect of anode width of dual schottky magnetodiode to sensitivity. The width is varied at 5, 15 and 35 μm with the forward bias 0.2 mA and reverse bias 0.25 nA. The applied magnetic field is varied from -0.4 T - 0.4 T. The output response DID is the cathode current difference. The best relative sensitivity SR is 54.6 mT-1 in the case of reverse bias at WA= 5 μm. The worst SR is 26.9 mT-1in the case of forward bias at WA= 35 μm. It depends on the ratio of the distance of deviation current in Y direction (DY) to the width of anode WA. It shows that the width WA should be design as narrow as possible and the operating current should be kept as low as one can. The current density from simulation can explain the mechanism of the device.

The study of forward and reverse schottky junction for dual magnetodiode

This paper presents schottky diode for sensing magnetic field. The structure is the same as dual magnetodiode that had been reported by the same group. The device can operate both in forward and reverse biasing for magnetic field device. The sensitivity (ΔVo/ΔB) by simulation of forward bias is 0.8 mV/T at the current 1.93 μA and reverse bias is 6 nV/T at the current 13.49 pA . Two modes of operation show linearity which electron is the only type of carrier. The mechanism of forward and reverse modes of operation are described.

Investigation on temperature effect on alcohol sensing of multi-walled carbon nanotube

This research studied the environment temperature affect to alcohol detecting and heated carbon nanotube film after alcohol detecting for a good chemical sensor application. The results showed that at the environment temperature below the room temperature (in this work −5 °C), the percentage of resistance changing is 15.70 % while at the 85 °C is 3.35 %. The heated CNT film after alcohol absorption during detecting time reduces the recovery time of the measurement cycle and reduces the minimum base resistance so increasing sensitivity of ΔR of CNT sensor. The results show that ΔR reaches to 76.22 % at environment temperature −5 °C, heating temperature 85 °C, and recovery time is faster than in the case of room temperature and no heating the film.

The Study of p-n and Schottky Junction for Magnetodiode

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.

Quartz Crystal Microbalance Coated with 18-Crown-6 Ether Film for 2,4,6-Trinitrotolurene (TNT) Vapor Detection

The 2, 4, 6-trinitrotoluene (TNT) vapor detection by quartz crystal microbalance (QCM) coated with 18-crown-6 ether film is introduced. The film acts as selective or sensitive layer for detecting TNT molecule. The frequency shift response is depend on the amount of mass of molecule adhere on the coated film surface. In this study, the concentrations of TNT vapor which is related to responses are studied. It shows that the TNT vapor concentration is related to the time for steady state condition and the frequency shift response. The high concentration vapor will increase the frequency shift response but increase the steady state time.