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Effects of High-energy Ni-ion Irradiation in the InAlGaN/GaN Heterostructure
M.Senthil Kumar,Y.S. Lee,S.J. Chung,C.-H. Hong,E.-K. Suh 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2
We report the effects of high-energy Ni-ion irradiation on the properties of the InAlGaN/GaN heterostructure grown on c-plane sapphire substrates by using a low-pressure metal organic chemical vapor deposition system. The heterostructure was irradiated with 100 MeV Ni ions for a fluence of 5 × 1012 cm−2 at room temperature. The X-ray rocking curve (0002) full width at half maximum (FWHM) value of the as-grown InAlGaN layer was measured to be 250 arcsec and was not affected by Ni-ion irradiation. However, the PL peak intensity of the heterostructure was completely quenched after ion irradiation, and its electrical properties turned to be highly insulating due to irradiation-induced defects. These results indicate that optical and electrical isolation is feasible in InAlGaN/GaN devices without damaging the crystalline quality by using the Ni-ion irradiation. The thermal annealing process could partly recover the optical and electrical properties of the heterostructure whereas, the junction properties of Schottky contacts fabricated on InAlGaN layer could not be restored. We report the effects of high-energy Ni-ion irradiation on the properties of the InAlGaN/GaN heterostructure grown on c-plane sapphire substrates by using a low-pressure metal organic chemical vapor deposition system. The heterostructure was irradiated with 100 MeV Ni ions for a fluence of 5 × 1012 cm−2 at room temperature. The X-ray rocking curve (0002) full width at half maximum (FWHM) value of the as-grown InAlGaN layer was measured to be 250 arcsec and was not affected by Ni-ion irradiation. However, the PL peak intensity of the heterostructure was completely quenched after ion irradiation, and its electrical properties turned to be highly insulating due to irradiation-induced defects. These results indicate that optical and electrical isolation is feasible in InAlGaN/GaN devices without damaging the crystalline quality by using the Ni-ion irradiation. The thermal annealing process could partly recover the optical and electrical properties of the heterostructure whereas, the junction properties of Schottky contacts fabricated on InAlGaN layer could not be restored.
Senthil Kumar, M,Park, J Y,Lee, Y S,Chung, S J,Hong, C-H,Suh, E-K Institute of Physics [etc.] 2007 Journal of Physics. D, Applied Physics Vol.40 No.17
<P>Surface morphology of green InGaN/GaN multi-quantum wells (MQWs) on a sapphire substrate with various high temperature grown GaN barriers has been evaluated. Keeping the InGaN well growth temperature constant at 740 °C, a series of MQWs were grown with GaN barrier temperatures varied up to 910 °C. GaN barriers grown below 800 °C lead to the generation of a high density of V-defects and inclusions embedded within V-defects as observed by atomic force microscopy. Scanning electron microscopy and cathodoluminescence (CL) studies revealed that the embedded inclusions are of two kinds: one of them appears as bright spots in CL mapping while the other appears as the surrounding region. Temperature ramping and subsequent interruption for GaN barrier growth suppresses both kinds of inclusion defects and also significantly reduces the V-defect density. An inclusion-free smooth surface is obtained for green emitting InGaN/GaN MQWs with the GaN barrier grown at 910 °C.</P>
M.Senthil Kumar,K.Mahadevan 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.2
Proportional Integral Derivative (PID) controller tuning is an area of interest for researchers in many areas of science and engineering. This paper presents a new algorithm for PID controller tuning based on a combination of bacteria foraging and particle swarm optimization. BFO algorithm has recently emerged as a very powerful technique for real parameter optimization. To overcome delay in an optimization, combine the features of BFOA and PSO for tuning the PID controller. This new algorithm is proposed to combine both the algorithms to get better optimization values. The real time prototype model of paper machine is designed and controlled by using PIC microcontroller embedded with the programming in C language.
Senthil Kumar, M.,Mahadevan, K. The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.2
Proportional Integral Derivative (PID) controller tuning is an area of interest for researchers in many areas of science and engineering. This paper presents a new algorithm for PID controller tuning based on a combination of bacteria foraging and particle swarm optimization. BFO algorithm has recently emerged as a very powerful technique for real parameter optimization. To overcome delay in an optimization, combine the features of BFOA and PSO for tuning the PID controller. This new algorithm is proposed to combine both the algorithms to get better optimization values. The real time prototype model of paper machine is designed and controlled by using PIC microcontroller embedded with the programming in C language.
Kumar, R Sambath,Sivakumar, T,Senthil, V,Murthy, N Venkateswara,Balasubramaniam, V,Sabi, R Kanaga,Sundram, R. Shanmuga,Perumal, P,Mazumder, U K,Gupta, M Kyung Hee Oriental Medicine Research Center 2008 Oriental pharmacy and experimental medicine Vol.8 No.2
The methanol extract of stem barks of Careya arborea Roxb. (MECA) (Family- Myrtaceae) was evaluated for antitumor activity and antioxidant status against Ehrlich's Ascites Carcinoma (EAC) bearing Swiss albino mice. After 24 h of tumor inoculation the MECA was administered at the doses of 50, 100 and 200 mg/kg body weight/mice/day for 14 days. After the last dose and 18 h fasting mice were sacrificed. The effect of MECA on the growth of transplantable murine tumor, life span of EAC bearing hosts, hematological profiles, serum and liver biochemical parameters were estimated. The MECA showed significant (P < 0.01) decrease in ascites volume, packed cell volume and viable cell count and prolonged the life span of EAC tumor bearing mice. Hematological profiles reverted to more or less normal levels in extract treated mice. The MECA also produced protective effect by decreasing the activity of serum enzymes, bilirubin and increase the protein and uric acid levels. MECA significantly (P < 0.05) decreased the levels of lipid peroxidation, while significantly (P < 0.05) increased the levels of glutathione content, vitamin C, vitamin E, superoxide dismutase and catalase CAT. The results indicate that MECA exhibited significant antitumor and antioxidant activity in EAC bearing mice.
M. Ravindran,S. Senthil Kumar,N. Karuppiah,M. Asokan 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.1
Insulators flashover is one of the major problem that confronts all around the world, particularly in austere weather conditionsand highly polluted areas. Any failure in the acceptable performance of high voltage insulators result in intrerruption ofelectrical power that leads to loss of capital. Flashover voltage (FOV) is directly related to the severity of pollution on thesurface of insulator. Generally, anti-pollution flashover coating is considered as one of the most effective means to prevent andreduce flashover. This paper investigates and compares the results on application of Epoxy Resin and Room TemperatureVulcanized (RTV) Silicone Rubber for improving the performance of outdoor (near coastal thermal plant area) insulators of12 KV rating. The flash over voltage of the insulators is optimized for a polluted environment by applying the protectivecoating and tested experimentally. The experimental results are compared with simulated results using Artificial NeuralNetwork.
M.N.A. GulshanTaj,Anupam Chakrabarti,R. Malathy,S.R.R. Senthil Kumar 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.3
Owing to the increase in demand for composite materials for different applications in aircraft structures, the nonlinear response of functionally graded ceramic-metal sandwich plates under mechanical loading is studied in the present research work. Geometric nonlinearity (GNL) is considered by Green-strain components and further assumes the form of von Kármán strains. It is ascertained that the effective mechanical properties vary through the thickness direction as a function of volume fraction of ceramic and metal constituents and obeys power law equation. Higher order displacement model proposed by Reddy is incorporated in the study to arrive for 2D isoparametric finite element C0 formulation. A nine node Lagrangian element is accomplished to model the assumed plate geometry. Different thickness schemes are proposed to model the sandwich plate with graded layer as core/ face sheets. Although the model can handle thickness scheme of any kind, results are exposed for four types of symmetric sandwich plates. Comparison statement between isotropic and graded plates is drawn in each case by appropriate selection of power law exponent value. The present investigation may be useful for design engineers/researchers to arrive for particular thickness scheme based on the results, while performing large deformation analysis of functionally graded sandwich plates (FGSP).
( T. Senthil Kumar ),( V. Balasubramanian ),( S. Babu ),( M. Y. Sanavullah ) 대한금속재료학회 ( 구 대한금속학회 ) 2007 METALS AND MATERIALS International Vol.13 No.4
AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of food processing equipment, chemical containers, passenger cars, road tankers, and railway transport systems. The preferred process for welding these aluminium alloys is frequently Gas Tungsten Arc (GTA) welding due to its comparatively easy applicability and lower cost. In the case of single pass GTA welding of thinner sections of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current processes. The use of pulsed current parameters has been found to improve the mechanical properties of the welds compared to those of continuous current welds of this alloy due to grain refinement occurring in the fusion zone. In this investigation, an attempt has been made to develop a mathematical model to predict the fusion zone grain diameter incorporating pulsed current welding parameters. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the mathematical model. The developed model can be effectively used to predict the fusion grain diameter at a 95 % confidence level for the given pulsed current parameters. The effect of pulsed current GTA welding parameters on the fusion zone grain diameter of AA 6061 aluminium alloy welds is reported in this paper.