Papers by Author: Amporn Poyai

Abstract: This paper studies the aspect ratio (W/L), width (W) per length (L) of semiconductor resistor based on Hall effect current mode for horizontal magnetic field. At low concentration, 10¹⁴ cm^-3, W/L < 1, the length has direct effect to magnetoresistance. The W/L = 1, the large resistor provides magnetioresistance better than small device. The W/L ˃ 1, the width has inversely proportional to magnetoresistance. The %MR(B) is around 1 % at 0.5 T, 1 mA. The long resistor (W/L < 1) can create ΔR in the order of several kilo ohms and several hundred ohms for short resistor (W/L > 1). The contribution factors ρ (L/W) for high ΔR are low concentration and aspect ratio (W/L < 1). The high %MR(B) is contributed by high current density of short structure (W/L > 1). At high concentration 10¹⁷ cm^-3, aspect ratio and magnetoresistance are not sensitive to magnetic field because the Hall effect hardly occurs in high concentration material.

Abstract: 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 DI_D is the cathode current difference. The best relative sensitivity S_R is 54.6 mT^-1 in the case of reverse bias at W_A= 5 μm. The worst S_R is 26.9 mT^-1in the case of forward bias at W_A= 35 μm. It depends on the ratio of the distance of deviation current in Y direction (DY) to the width of anode W_A. It shows that the width W_A 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.

Abstract: This paper presented the corresponding between the yield equation prediction from Poisson, Murphy with wafer actual yield on the silicon wafer with 0.8 μm CMOS technology. The defect analysis with derivative method, current - voltage and capacitance-voltage of diode characteristic measurement, is used to define the defect in p-n junction on silicon wafer. The different sampling numbers of chips are used to calculate the yield. Finally the calculated data and actual would be compared and found that at sampling number is 25, the tolerance from actual yield is less than 3%.

Abstract: Cancer is one of the leading causes for human death. However, if cancer cells are identified at initial stage, patient treatment will be low cost and successful. This research presents the design and simulation of ascending curvilinear micro channel for separation of particles resembling cancer cells. The separation system is designed and simulated by using inertia focusing cell separation technique. Computational fluid dynamics (CFD) design and simulation of ascending micro channel for cell separation using inertial focusing technique is used for separation. The simulation was carried in two stages; for focusing and separation. The mixture flow velocities were 0.105 m/s, 115 m/s and 125 m/s, and with Reynolds number Re = 8.5, 9.25 and 10.06. The ascending curvilinear channel design demonstrated favorable focusing, and separation. 100% purity and 100 % efficiency for separation of 15 µm particles was achieved at Re = 8.50 and maximum output/input ratio at velocity 0.105m/s. Cancer cells are also of size about 15 µm and the our proposed micro channel is a good candidate for cancer cells separation from blood.

Abstract: This paper is proposed to extract the local carrier generation lifetime from forward current-voltage (I-V) characteristics of p-n junctions in case of non-uniform defects. The different geometry p-n junctions have been fabricated by a standard CMOS technology. The forward I-V and high frequency capacitance-voltage (C-V) characteristics of p-n junctions have been measured. The recombination current density can be extracted from the area forward current density by subtracting with the area diffusion current density. Form the recombination current density, the local generation and recombination lifetime can be obtained.

Abstract: 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.

Abstract: This paper investigates the effect of soft X-ray irradiation various energy and times on P-N junction diodes. X-ray energy irradiated on P-N junction diode with 55 and 70 keV with various time in the range 5-50 sec. After irradiations were study on the current-voltage (I-V) characteristics and capacitance-voltage (C-V) characteristics. Leakages current after irradiated by X-ray are not change, while forward current are increase about 3 orders. The change of current-voltage characteristics can analyze by many parameter such as carrier lifetime and series resistance. Capacitance-voltage characteristics after irradiation are not change. The results show that soft X-ray technique can be improving performance of the P-N junction diodes. These techniques are importance to use for improving device performance in industry work.

Abstract: Diode leakage current consists of diffusion (I_d) and generation current (I_g), which is strongly sensitive to the residual defect density. These defects can be studied by activation energy (E_a). Therefore, this paper presents a method for calculating activation energy of silicon p-n junctions from volume generation current. It combines temperature-dependent current–voltage (I –V) and capacitance–voltage (C-V) measurements of diodes. The I_g can be found from the volume leakage current by subtraction of the volume diffusion current, which is calculated while the depletion width is zero. The activation energy (E_a) is derived from slope of an Arrhenius plot of I_g. To derive the correct slope the temperature dependence of the depletion width, which is obtained from the corrected volume capacitance has been applied. The E_a profile below junction has been shown. The lower E_a value has been found near the junction, which may relate to the junction implantation.

Abstract: An effect induced by x-ray irradiation on Boron-doped crystalline Si at room temperature was closely investigated in this paper. Irradiation of X-ray energy of 40, 55 and 70keV has been performed on P-N junction diodes fabricated at Thai Microelectronics Center. Minority carrier life time of the device has been calculated before and after irradiation for comparison. The results show no significant change on the value between exposed and unexposed device. Therefore, any permanent lattice modified or any defects caused by X-ray in the device bulk seem to be unconfirmed in this range of energy. However, from this study, X-ray irradiation still effects on electrical characteristics of the diodes. Current-voltage (I-V) measurement has been carried out to study characteristic variation of the device. Biasing of the device was performed from -10 to 1 V and, after the exposure, the leakage current was obviously decreased by 25% and forward current was dramatically increased by 3 order of magnitude related to increment of X-ray energy.

Abstract: Titanium nitride (TiN) film has been widely used as a diffusion barrier layer for VLSI contact metallization because TiN is an excellent barrier against inter-diffusion between Al and Si substrate or silicide. In this work, we studied the properties of TiN films deposited by DC magnetron sputtering with varying N2:Ar flow rate ratio in order to optimize growth conditions and film properties provided for Al diffusion barrier purpose. The TiN films were deposited at the constant pressure level and sputtering time. The crystalline orientation, composition and electrical properties of deposited TiN films were characterized by XRD, AES-depth profile and Four Point Probe measurement, respectively. The XRD results show that the deposited TiN film has two preferred orientations of TiN(111) and TiN(200) planes. The highest intensity of the TiN(111) plane was obtained when the N2:Ar flow rate ratio was 3:1. The electrical resistivity was increased when the N2:Ar flow rate ratio was decreased. The minimum electrical resistivity is 127.8 μΩ-cm when the N2:Ar flow rate ratio is 3:1.