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RISS 인기검색어
- 검색키워드
- 저자 : A. Rudra (검색결과 3 건)
- 무료
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Optically Controlled Silicon MESFET Modeling Considering Diffusion Process
S. N. Chattopadhyay,N. Motoyama,A. Rudra,A. Sharma,S. Sriram,C. B. Overton,P. Pandey 대한전자공학회 2007 Journal of semiconductor technology and science Vol.7 No.3
An analytical model is proposed for an optically controlled Metal Semiconductor Field Effect Transistor (MESFET), known as Optical Field Effect Transistor (OPFET) considering the diffusion fabrication process. The electrical parameters such as threshold voltage, drain-source current, gate capacitances and switching response have been determined for the dark and various illuminated conditions. The Photovoltaic effect due to photogenerated carriers under illumination is shown to modulate the channel cross-section, which in turn significantly changes the threshold voltage, drainsource current, the gate capacitances and the device switching speed. The threshold voltage VT is reduced under optical illumination condition, which leads the device to change the device property from enhancement mode to depletion mode depending on photon impurity flux density. The resulting I-V characteristics show that the drain-source current IDS for different gate-source voltage Vgs is significantly increased with optical illumination for photon flux densities of Φ = 10<SUP>15</SUP> and 10<SUP>17</SUP> /㎠s compared to the dark condition. Further more, the drain-source current as a function of drain-source voltage VDS is evaluated to find the I-V characteristics for various pinch-off voltages VP for optimization of impurity flux density QDiff by diffusion process. The resulting I-V characteristics also show that the diffusion process introduces less process-induced damage compared to ion implantation, which suffers from current reduction due to a large number of defects introduced by the ion implantation process. Further the results show significant increase in gate-source capacitance Cgs and gate-drain capacitance Cgd for optical illuminations, where the photo-induced voltage has a significant role on gate capacitances. The switching time τ of the OPFET device is computed for dark and illumination conditions. The switching time τ is greatly reduced by optical illumination and is also a function of device active layer thickness and corresponding impurity flux density QDiff. Thus it is shown that the diffusion process shows great potential for improvement of optoelectronic devices in quantum efficiency and other performance areas.
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Optically Controlled Silicon MESFET Modeling Considering Diffusion Process
Chattopadhyay, S.N.,Motoyama, N.,Rudra, A.,Sharma, A.,Sriram, S.,Overton, C.B.,Pandey, P. The Institute of Electronics and Information Engin 2007 Journal of semiconductor technology and science Vol.7 No.3
An analytical model is proposed for an optically controlled Metal Semiconductor Field Effect Transistor (MESFET), known as Optical Field Effect Transistor (OPFET) considering the diffusion fabrication process. The electrical parameters such as threshold voltage, drain-source current, gate capacitances and switching response have been determined for the dark and various illuminated conditions. The Photovoltaic effect due to photogenerated carriers under illumination is shown to modulate the channel cross-section, which in turn significantly changes the threshold voltage, drainsource current, the gate capacitances and the device switching speed. The threshold voltage $V_T$ is reduced under optical illumination condition, which leads the device to change the device property from enhancement mode to depletion mode depending on photon impurity flux density. The resulting I-V characteristics show that the drain-source current IDS for different gate-source voltage $V_{gs}$ is significantly increased with optical illumination for photon flux densities of ${\Phi}=10^{15}\;and\;10^{17}/cm^2s$ compared to the dark condition. Further more, the drain-source current as a function of drain-source voltage $V_{DS}$ is evaluated to find the I-V characteristics for various pinch-off voltages $V_P$ for optimization of impurity flux density $Q_{Diff}$ by diffusion process. The resulting I-V characteristics also show that the diffusion process introduces less process-induced damage compared to ion implantation, which suffers from current reduction due to a large number of defects introduced by the ion implantation process. Further the results show significant increase in gate-source capacitance $C_{gs}$ and gate-drain capacitance $C_{gd}$ for optical illuminations, where the photo-induced voltage has a significant role on gate capacitances. The switching time ${\tau}$ of the OPFET device is computed for dark and illumination conditions. The switching time ${\tau}$ is greatly reduced by optical illumination and is also a function of device active layer thickness and corresponding impurity flux density $Q_{Diff}$. Thus it is shown that the diffusion process shows great potential for improvement of optoelectronic devices in quantum efficiency and other performance areas.
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Md. Adnan,Md. Nazim Uddin Chy,Sajib Rudra,Afroza Tahamina,Raju Das,Mohammad Akramul Hoque Tanim,Tanvir Iqram Siddique,Asadul Hoque,Syeda Mashnia Tasnim,Arkajyoti Paul,A. T. M. Mostafa Kamal 경희대학교 융합한의과학연구소 2019 Oriental Pharmacy and Experimental Medicine Vol.19 No.2
This study was conducted to investigate the antioxidant, antibacterial, anthelmintic, and cytotoxic activities of the crude methanol extract of Bonamia semidigyna (Roxb.) leaves and its derived fractions in different experimental models. Leaves of B. semidigyna were extracted with methanol (MBS) and the resultant successively fractionated into n-hexane (NBS), petroleum ether (PBS), chloroform (CBS), and ethyl acetate (EBS) soluble fractions. Later, the plant extractives were investigated for antioxidant, antibacterial, anthelmintic and cytotoxic properties. Phytochemical study was carried out using standard methods and polyphenols content were determined by spectrophotometric techniques. Antioxidant activity was evaluated by DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity, hydrogen peroxide ( H2O2) scavenging activity, ferric reducing power, and total antioxidant capacity assays. Disc diffusion technique used to evaluate the antibacterial efficacy and anthelmintic activity was determined using aquarium worm (Tubifex tubifex) whereas cytotoxicity was evaluated using brine shrimp lethality bioassay. The phytochemical study revealed the presence of alkaloids, flavonoids, terpenoids, tannins, saponins, phenolic, steroids, sterols, quinones, oxalate, coumarins, and emodins in the plant extractives. In addition, the quantitative phytochemical analysis showed the significant amount of polyphenol contents. In antioxidant assays, the crude methanol extract and EBS fraction exhibited the most potent antioxidant activity among all the extractives. The crude methanol extract and EBS fraction also possessed significant antibacterial and anthelmintic potentials while moderate cytotoxic activities were found for all the plant extractives. The present study confirmed that the crude methanol extract of B. semidigyna and its EBS fraction, possibly due to its high polyphenol contents possess significant antioxidant, antibacterial, and anthelmintic properties.
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