Electrical transport properties of Au/SiO2/n-GaN MIS structure in a wide temperature range

B. Prasanna Lakshmi,M. Siva Pratap Reddy,A. Ashok Kumar,V. Rajagopal Reddy 한국물리학회 2012 Current Applied Physics Vol.12 No.3

The temperature-dependent electrical properties of Au/SiO2/n-GaN metal-insulator-semiconductor (MIS)structure have been investigated in the temperature range of 120e390 K. Anomalous strong temperature dependencies of the barrier height (φbo), ideality factor (n), interface state density (NSS) and series resistance (RS) are obtained. Such behaviour is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights (GD BHs) at the interface. It is evident that the diode parameters such as zero-bias barrier height increases and the ideality factor decreases with increasing temperature. The values of series resistance that are obtained from Cheung’s method is decreasing with increasing in temperature. The temperature-dependent currentevoltage characteristics of the MIS diode have been shown a double Gaussian distribution giving mean barrier heights of 0.38 eV and 1.06 eV and standard deviations of 0.0561 and 0.2742 V, respectively. A modified ln (Io/T2) - q2so 2/2k2T2 versus 103/T plot for the two temperature regions gives 4bo and A* as 0.55 eV and 11.56 A cm-2 K-2, and 1.02 eV and 23.48 A cm-2 K-2 respectively. The Interface state density values are calculated by IeV and CeV measurements at different temperatures using Terman’s method. It is observed that the interface state density decreases with increase in temperature (120e390 K). Therefore, it has been concluded that the temperature dependence of the forward IeV characteristics of the Au/SiO2/n-GaN Schottky diodes can be explained with a double GD of the BHs.

Analysis of electrical characteristics of Er/p-InP Schottky diode at high temperature range

A. Ashok Kumar,L. Dasaradha Rao,V. Rajagopal Reddy,최철종 한국물리학회 2013 Current Applied Physics Vol.13 No.6

We report on the temperature-dependent electrical characteristics of Er/p-InP Schottky barrier diodes. The currentevoltage (IeV) and capacitanceevoltage (CeV) measurements have been carried out in the temperature range of 300e400 K. Using thermionic emission (TE) theory, the zero-bias barrier height (Fbo) and ideality factor (n) are estimated from IeV characteristics. It is observed that there is a decrease in n and an increase in the Fbo with an increase in temperature. The barrier height inhomogenity at the metal/semiconductor (MS) interface resulted in Gaussian distribution of Fbo and n. The laterally homogeneous Schottky barrier height value of approximately 1.008 eV for the Er/p-InP Schottky barrier diodes is extracted from the linear relationship between the experimental zero-bias barrier heights and ideality factors. The series resistance (Rs) is calculated by Chenug’s method and it is found that it increases with the decrease in temperature. The reverse-bias leakage current mechanism of Er/p-InP Schottky diode is investigated. Both PooleeFrenkel and Schottky emissions are described and discussed. Furthermore, capacitanceevoltage (C eV) measurements of the Er/p-InP Schottky contacts are also carried out at room temperature in dark at different frequencies of 10, 100 and 1000 kHz. Using Terman’s method, the interface state density is calculated for Er/p-InP Schottky diode at different temperatures.

Electrical Properties of Pt/n-Ge Schottky Contact Modified Using Copper Phthalocyanine (CuPc) Interlayer

Kumar, A. Ashok,Reddy, V. Rajagopal,Janardhanam, V.,Seo, Min-Woo,Hong, Hyobong,Shin, Kyu-Sang,Choi, Chel-Jong The Electrochemical Society 2012 Journal of the Electrochemical Society Vol.159 No.1

Electrical properties of Pt/n-type Ge Schottky contact with PEDOT:PSS interlayer

Ashok Kumar, A.,Rajagopal Reddy, V.,Janardhanam, V.,Yang, H.D.,Yun, H.J.,Choi, C.J. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.549 No.-

The effect of poly (3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) interlayer on the Schottky barrier parameters of Pt/n-type Ge Schottky contacts was investigated. The PEDOT:PSS interlayer in between Pt and n-type Ge influences the space charge region of the Pt/n-type Ge Schottky junction, leading to increase in the barrier height. Due to interface dipoles and lateral barrier inhomogeneities caused by the presence of PEDOT:PSS interlayer, Pt/PEDOT:PSS/n-type Ge Schottky contact showed a deviation from the ideal thermionic emission model of the carrier transport at the metal/semiconductor junction. From the reverse current-voltage (I-V) characteristics, the Poole-Frenkel emission and Schottky emission were found to be the dominating carrier conduction mechanisms of Pt/PEDOT:PSS/n-type Ge Schottky contact at lower and higher reverse biases, respectively.

Analysis of electrical characteristics of Er/p-InP Schottky diode at high temperature range

Ashok Kumar, A.,Dasaradha Rao, L.,Rajagopal Reddy, V.,Choi, C.J. Elsevier 2013 Current Applied Physics Vol.13 No.6

We report on the temperature-dependent electrical characteristics of Er/p-InP Schottky barrier diodes. The current-voltage (I-V) and capacitance-voltage (C-V) measurements have been carried out in the temperature range of 300-400 K. Using thermionic emission (TE) theory, the zero-bias barrier height (Φ<SUB>bo</SUB>) and ideality factor (n) are estimated from I-V characteristics. It is observed that there is a decrease in n and an increase in the Φ<SUB>bo</SUB> with an increase in temperature. The barrier height inhomogenity at the metal/semiconductor (MS) interface resulted in Gaussian distribution of Φ<SUB>bo</SUB> and n. The laterally homogeneous Schottky barrier height value of approximately 1.008 eV for the Er/p-InP Schottky barrier diodes is extracted from the linear relationship between the experimental zero-bias barrier heights and ideality factors. The series resistance (R<SUB>s</SUB>) is calculated by Chenug's method and it is found that it increases with the decrease in temperature. The reverse-bias leakage current mechanism of Er/p-InP Schottky diode is investigated. Both Poole-Frenkel and Schottky emissions are described and discussed. Furthermore, capacitance-voltage (C-V) measurements of the Er/p-InP Schottky contacts are also carried out at room temperature in dark at different frequencies of 10, 100 and 1000 kHz. Using Terman's method, the interface state density is calculated for Er/p-InP Schottky diode at different temperatures.

Design of Octagonal CPW-Fed Broadband Millimeter Wave Antenna for 5G Applications

S. Ashok Kumar,T. Shanmuganantham,D. Sindhaniselvi,A. L. Sharon Giftsy 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.2

A CPW-fed antenna is designed with octagonal shaped patch operating at a broadband millimeter-wave frequency from 24.8 to 48.8 GHz for wireless 5G applications. The antenna was design with dimensions of 20 × 20 × 1.6 mm 3 are made with low cost FR4 loss free substrate with dielectric constant (ε r ) of 4.3 using the CST Microwave Studio software. Simulated radiation pattern and return loss < -10 dB is achieved at a frequency of 28 GHz, 30.78 GHz, 38 GHz, 41.64 GHz and 44.16 GHz with the gain of 5.1 dB, 6.39 dB, 6.59 dB, 7.48 dB and 7.04 dB. The voltage standing wave ratio (VSWR) < 2 at (24.8–48.8) GHz which indicates that these frequencies operated by the antenna has minimum reflection.

Radioprotective and Antioxidant Activity of Fractionated Extracts of Berries of Hippophae rhamnoides

Rakesh Kumar Sharma,Raman Chawla,Rajesh Arora,Shikha Singh,Ravinder Kumar Sagar,Raj Kumar,Ashok Sharma,Manju L. Gupta,Surender Singh,Jagdish Prasad,Haider A. Khan,Anand Swaroop,A.K. Sinha,A.K. Gupta,R 한국식품영양과학회 2007 Journal of medicinal food Vol.10 No.1

Plants are an abundant source of medicinal compounds, some of which are useful in combating free radical-1002 (flavonoid-poor fraction) of Hippophae rhamnoideswere screened on the basis of their reducing power in the aqueousphase. REC-1001 was selected for further study, since it exhibited 27.38 times higher antioxidant activity than REC-1002.REC-1001 also showed significant (P. .05) membrane protection potential at 50 .g/mL, which was attributed to its abilityto scavenge peroxyl radicals (64.82. 1.25% scavenging within 1,440 min). A significant (P. .05) difference of 67.02% infree radical scavenging activity at 1,000 ng/mL between REC-1001 and vitamin E demonstrated the extract fraction’s worthc-tion. Further, REC-1001 was found to be nontoxic up to 200 mg/kg of body weight. This research suggests that the REC-1001 fraction of H. rhamnoidesextract is a safe and effective antioxidant nutraceutical product.

An Explainable Deep Learning Approach for Oral Cancer Detection

Babu P. Ashok,Rai Anjani Kumar,Ramesh Janjhyam Venkata Naga,Nithyasri A.,Sangeetha S.,Kshirsagar Pravin R.,Rajendran A.,Rajaram A.,Dilipkumar S. 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

With a high death rate, oral cancer is a major worldwide health problem, particularly in low- and middle-income nations. Timely detection and diagnosis are crucial for efective prevention and treatment. To address this challenge, there is a growing need for automated detection systems to aid healthcare professionals. Regular dental examinations play a vital role in early detection. Transfer learning, which leverages knowledge from related domains, can enhance performance in target categories. This study presents a unique approach to the early detection and diagnosis of oral cancer that makes use of the exceptional sensory capabilities of the mouth. Deep neural networks, particularly those based on automated systems, are employed to identify intricate patterns associated with the disease. By combining various transfer learning approaches and conducting comparative analyses, an optimal learning rate is achieved. The categorization analysis of the reference results is presented in detail. Our preliminary fndings demonstrate that deep learning efectively addresses this challenging problem, with the Inception-V3 algorithm exhibiting superior accuracy compared to other algorithms.

Role of Cytocentrifugation Combined with Nuclear Fast Picroindigocarmine Staining in Detecting Cryptozoospermia in Men Diagnosed with Azoospermia

Sharma Rakesh Kumar,Gupta Sajal,Agarwal Ashok,Finelli Renata,Kuroda Shinnosuke,Saleh Ramadan,Boitrelle Florence,Kavoussi Parviz,Gül Murat,Tadros Nicholas,Ko Edmund,Farkouh Ala’a,Henkel Ralf,Arafa Moha 대한남성과학회 2022 The World Journal of Men's Health Vol.40 No.4

Purpose: Azoospermia is defined as the absence of spermatozoa in the pellet of a centrifuged semen sample. In fact, when a basic semen analysis fails to detect sperm in the ejaculate, there is still the possibility of detecting rare sperm after centrifugation of the sample and examination of the pellet. In this study, we assessed the role of Cytospin centrifugation in combination with the nuclear fast picroindigocarmine (NF-PIC) staining in identifying sperm in azoospermic samples. Materials and Methods: Semen samples of 251 men diagnosed as having azoospermia after standard examination were further analyzed by Cytospin centrifugation in combination with NF-PIC staining. Results: Sperm were detected in 60 men (23.9%), thus changing their diagnosis to cryptozoospermia. Conclusions: By identifying sperm in the semen of men who were thought to have total azoospermia, the Cytospin NF-PIC test can alter the diagnosis and further treatment of these men.

Microstructural and chemical properties of Cu‐In alloys formed using co‐electrodeposition

Moon, Kyung‐,Won,Ashok Kumar, A.,Lee, Young‐,Boo,Park, Yang‐,Kyu,Choi, Chel‐,Jong John Wiley Sons, Ltd 2012 Surface and interface analysis Vol.44 No.11

<P>We investigated the microstructural and chemical properties of Cu‐In alloys formed on Au‐coated Si substrates using co‐electrodeposition. The co‐electrodeposition was performed using electrolytic solutions with various molar ratios of CuCl<SUB>2</SUB> and InCl<SUB>3</SUB> (1 mM/5 mM, 2 mM/4 mM, and 5 mM/5 mM) at room temperature. With increased electrodeposition current, the concentrations of Cu and In atoms in the Cu‐In alloys decreased and increased, respectively. Because of the preferential growth of Cu, a decrease in the molar ratio of CuCl<SUB>2</SUB> and InCl<SUB>3</SUB> led to a reduction in the minimum electrodeposition current that is required to obtain Cu‐In alloys with the same concentration of Cu and In atoms. The increases in electrodeposition current and the molar ratio of CuCl<SUB>2</SUB> and InCl<SUB>3</SUB> facilitated the formation of Cu‐In dendrites with long central trunks and secondary branches. The dendrites could be associated with autocatalytical alloy growth driven by a concentric diffusion field of metal ions on a thermodynamically unstable surface. During co‐electrodeposition using electrolytic solution (CuCl<SUB>2</SUB> = 1 mM and InCl<SUB>3</SUB> = 5 mM) under an electrodeposition current of 20 mA, the increase in the cathodic overpotential caused by surface irregularity led to the formation of Au‐In, which could be a main cause of the observed hillock formation. Copyright © 2012 John Wiley & Sons, Ltd.</P>