Highly Sensitive Flexible Photodetectors Based on Self-Assembled Tin Monosulfide Nanoflakes with Graphene Electrodes

Mohan Kumar, Ganesan,Fu, Xiao,Ilanchezhiyan, Pugazhendi,Yuldashev, Shavkat U.,Lee, Dong Jin,Cho, Hak Dong,Kang, Tae Won American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.37

<P>Tin monosulfide (SnS) nanostructures have attracted huge attention recently because of their high absorption coefficient, high photoconversion efficiencies, low energy cost, ease of deposition, and so on. Here, in this paper, we report on the low-cost hydrothermal synthesis of the self-assembled SnS nanoflake-like structures in terms of performance for the photodetectors. High-performance photodetectors were fabricated using SnS nanoflakes as active layers and graphene as the lateral electrodes. The SnS photodetectors exhibited excellent photoresponse properties with a high responsivity of 1.7 X 10(4) A/W and have fast response and recovery times. In addition, the photodetectors exhibited long-term stability and strong dependence of photocurrent on light intensity. These excellent characteristics were attributed to the larger surface-to-volume ratio of the self-assembled SnS nanoflakes and the effective separation of the photogenerated carriers at graphene/SnS interfaces. Additionally, a flexible photodetector based on SnS nanoflakes was also fabricated on a flexible substrate that demonstrated similar photosensitive properties. Furthermore, this study also demonstrates the potential of hydrothermal-processed SnS nanoflakes for high-performance photodetectors and their application in flexible low-cost optoelectronic devices.</P>

Solution processed n-In2O3nanostructures for organic-inorganic hybrid p-n junctions

Kumar, G. Mohan,Kumar, A. Madhan,Ilanchezhiyan, P.,Kang, T. W. The Royal Society of Chemistry 2014 Nanoscale Vol.6 No.19

<P>Solution processed organic-inorganic bulk hybrid heterostructures are nowadays considered as the most promising elements to perform efficient optoelectronic functions. In this regard, In2O3 based hybrid heterostructures were fabricated using polypyrrole and their role as efficient interfacial layers was studied using polypyrrole/ZnO nanowires. The In2O3 nanostructures were synthesized through a facile wet chemical approach at an average scale of less than 10 nm in cubic phase. The presence of O and In related defects was studied through emission spectra; these were also found to exhibit their predominance in Raman measurements. The n-type characteristics and donor density value of around 1020 cm-3 were evaluated for the In2O3 specimens via Mott-Schottky plots. The role of In2O3 nanostructures as active/interfacial layers was then studied using the current-voltage characteristics obtained across the hybrid heterostructures made of polypyrrole/In2O3, polypyrrole/ZnO and polypyrrole/In2O3/ZnO. Organic-inorganic p-n diodes were obtained via in situ chemical polymerization, drop casting and hydrothermal routes. Cyclic voltammograms and Nyquist plots were used to study the reduction mechanism taking place in the nanostructures that actually results with the formation of metallic In, which plays a vital role in establishing the required conduction electrons. The same has been reasoned for the improved rectification characteristics observed across the diodes.</P>

Electrochemical studies on two-dimensional ZnInO nanoplates for organic–inorganic hybrid photodiode related applications

Mohan Kumar, G.,Madhan Kumar, A.,Ilanchezhiyan, P.,Kang, T.W. Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.619 No.-

<P><B>Abstract</B></P> <P>An ultra low cost route has been established to fabricate organic–inorganic hybrid <I>p</I> <I>–</I> <I>n</I> junctions <I>via</I> chemical <I>in-situ</I> polymerization of organic monomers on traditionally drop casted inorganic deposits. In this regard, ZnInO nanoplate-like structures were synthesized through a facile solution based chemical approach and their structural property was studied using X-ray diffraction patterns. The nature of charge carriers and donor density in ZnInO made electrodes were studied using electrochemical impedance spectroscopy. The dissemination of polymer matrices on the ZnInO nanoplates was examined through scanning electron microscopy. The current–voltage characteristics obtained across the polypyrrole/ZnInO made hybrid structures revealed an improved rectifying behaviour under illuminated conditions. The mechanism behind the drastic decrease in resistance values that substantiates the improved electron transfer characteristics across the organic–inorganic structures was studied through cyclic voltammetric measurements.</P>

Cortical Auditory Event Related Potentials (P300) for Frequency Changing Dynamic Tones

Mohan Kumar Kalaiah,Usha Shastri 대한청각학회 2016 Journal of Audiology & Otology Vol.20 No.1

Background and Objectives: P300 has been studied with a variety of stimuli. However, the nature of P300 has not been investigated for deviant stimuli which change its characteristics from standard stimuli after a period of time from onset. Subjects and Methods: Nine young adults with normal hearing participated in the study. The P300 was elicited using an oddball paradigm, the probability of standard and deviant stimuli was 80% and 20% respectively. Six stimuli were used to elicit P300, it included two pure-tones (1,000 Hz and 2,000 Hz) and four tone-complexes (tones with frequency changes). Among these stimuli, 1,000 Hz tone served as standard while others served as deviant stimuli. The P300 was recorded in five separate blocks, with one of the deviant stimuli as target in each block. Electroencephalographic was recorded from electrode sites Fz, Cz, C3, C4, and Pz. Latency and amplitude of components of the cortical auditory evoked potentials were measured at Cz. Results: Waveforms obtained in the present study shows that, all the deviant stimuli elicited obligatory P1-N1-P2 for stimulus onset. 2,000 Hz deviant tone elicited P300 at a latency of 300 ms. While, tone-complexes elicited acoustic change complex (ACC) for frequency changes and finally elicited P300 at a latency of 600 ms. In addition, the results showed shorter latency and larger amplitude ACC and P300 for rising tone-complexes compared to falling tone-complexes. Conclusions: Tone-complexes elicited distinct waveforms compared to 2,000 Hz deviant tone. Rising tone-complexes which had an increase in frequency elicited shorter latency and larger amplitude responses, which could be attributed to perceptual bias for frequency changes.

In-Process Measurement of Surface Roughness using Machine Vision with Sub-Pixel Edge Detection in Finish Turning

Mohan Kumar Balasundaram,Mani Maran Ratnam 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

Common methods of in-process surface roughness measurement are capable of providing a limited number of amplitude parametersfor roughness assessment. This is mainly due to the averaging effect of the sensors used. In this work, we measured the amplitude,spacing, hybrid as well as functional surface roughness parameters during dry turning of AISI 1035 carbon steel using machinevision. A commercial DSLR camera with high shutter speed was used to capture a blur-free image of the workpiece surface profilediametrically opposite the cutting tool. The edge of the surface profile was detected to sub-pixel accuracy using the grey level invariantmoment and the roughness parameters were determined from the profile. The tool nose wear and machining time were correlated withamplitude, hybrid, and spacing surface roughness parameters, as well as the bearing area curve parameters. Three new roughnessparameters, namely average slope of profile peaks (Φp), average slope of profile valleys (Φv), relative length of peaks (Rrl), wereintroduced to study the effect of changes in tool nose micro geometry due to wear on the surface roughness. Among these newparameters Φp and Rrl showed better correlation with machining time and nose wear compared to all other parameters.

Fabrication of polypyrrole/ZnO nanowires based organic–inorganic hybrid p-n junctions

Mohan Kumar, G.,Madhan Kumar, A.,Ilanchezhiyan, P.,Kang, T. W. Springer Science + Business Media 2015 Journal of materials science Materials in electron Vol.26 No.4

Resource-efficient load-balancing framework for cloud data center networks

Kumar, Jitendra,Singh, Ashutosh Kumar,Mohan, Anand Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.1

Cloud computing has drastically reduced the price of computing resources through the use of virtualized resources that are shared among users. However, the established large cloud data centers have a large carbon footprint owing to their excessive power consumption. Inefficiency in resource utilization and power consumption results in the low fiscal gain of service providers. Therefore, data centers should adopt an effective resource-management approach. In this paper, we present a novel load-balancing framework with the objective of minimizing the operational cost of data centers through improved resource utilization. The framework utilizes a modified genetic algorithm for realizing the optimal allocation of virtual machines (VMs) over physical machines. The experimental results demonstrate that the proposed framework improves the resource utilization by up to 45.21%, 84.49%, 119.93%, and 113.96% over a recent and three other standard heuristics-based VM placement approaches.

Short Term Test-Retest Reliability of Contralateral Inhibition of Distortion Product Otoacoustic Emissions

Mohan Kumar Kalaiah,Alina Lasrado,Nikita Pinto,Usha Shastri 대한청각학회 2018 Journal of Audiology & Otology Vol.22 No.4

Background and Objectives: Strength of medial olivocochlear reflex can be measured reliably using contralateral inhibition of distortion product otoacoustic emissions (DPOAEs) when its fine structure is considered. However, measurement of fine structure of DPOAE is difficult with clinical equipment. Thus, this study investigated the clinically relevant test-retest reliability of contralateral inhibition of DPOAEs. Subjects and Methods: Twenty-six young adults withnormal hearing sensitivity participated. DPOAEs were recorded at 27 discrete f2 frequenciesbetween 800 Hz and 8,000 Hz at frequency resolution of 8 points per octave with and withoutcontralateral white noise presented at 50 dB SPL. To check for short term inter-sessionreliability, contralateral inhibition of DPOAEs were recorded in three sessions, two recordingsessions on first day separated by 30 minutes and third time after one week of the first session. Within each session, DPOAEs were recorded twice in single probe-fit condition to testfor intra-session reliability. Results: Cronbach’s alpha was calculated having poor reliability (α≤0.7) of contralateral inhibition of DPOAEs in both intra-session and inter-session conditionsfor most of the tested frequencies. 95% confidence intervals of contralateral inhibition magnitudealso showed large variability. Conclusions: The current results showed that thoughDPOAE amplitudes were highly reliable across sessions, amount of inhibition of DPOAEs wasnot reliable when DPOAEs were measured at discrete frequencies. These findings are concurrentwith the literature.

Effect of ethylenediamine tetra acetic acid additive on the nucleation kinetics and growth aspects of L-arginine phosphate single crystals

Kumar, R.Mohan,Babu, D.Rajan,Ravi, G.,Jayavel, R. The Korea Association of Crystal Growth 2003 韓國結晶成長學會誌 Vol.13 No.4

Pure and Ethylenediaminetetraacetic acid (EDTA) doped L-arginine phosphate (LAP) single crystals were grown from the aqueous solution by temperature lowering method. The effect of EDTA additive on the solubility and metastable zone width of LAP solution has been investigated. Addition of EDTA has enhanced the metastable zone width of LAP and hence bulk crystals could be grown. The growth rate along the [100] direction increases with EDTA additive. Powder X-ray diffraction and FTIR studies reveal the absence of EDTA in the lattice of LAP, This reveals that the addition of EDTA to LAP doesn't influence the crystallinity. However, the transmittance and NLO properties significantly increase with EDTA additive and hence bulk LAP crystals are useful for laser fusion experiments.

Numerical analysis of the effect of baffle orientation and baffle size on shell-side pressure drop in a liquefied natural gas (LNG) vaporizer

Mohan Kumar Dey,Hyun-Jong Kim,Yoon-Hwan Choi,Sung-Hoon Kim,Yeon-Won Lee 한국마린엔지니어링학회 2018 한국마린엔지니어링학회지 Vol.42 No.5