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페다티물라 푸네타(Peddathimula Puneetha),시바 프라탭 레디 말렘(Siva Pratap Reddy Mallem),이정희(Jung-Hee Lee),심재술(Jaesool Shim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
Recently, health-monitoring and wearable human-machine electronic devices have been receiving significant amount of attention. This means that these devices are possible to bending allowing free contacts to and conformal deformation on human skin and internal organs under physical/chemical changes. Current switching, which use change in current measurement data, is considered as one of the potential candidate for the next-generation sensing technology. The Schottky nano-junction that generally exhibits switching behavior may useful for switching sensors. GaN is an important optoelectronic wurtzite semiconductor material. GaN shows good mechanical performance and chemical stability even at higher temperatures. In addition, carbon-tape has high electrical/thermal conductivities, super-elastic mechanical properties. Especially, flexible GaN/carbon-tape, a dual-material that exhibits piezo-electrical properties, is likely a good candidate for fabricating Schottky nano-junction-based switching sensors.
DNA-CTMA/a-Si:H bio-hybrid photodiode: A light-sensitive photosensor
Reddy, M. Siva Pratap,Puneetha, P.T.,Lee, Young-Woong,Jeong, Seong-Hoon,Park, Chinho Elsevier 2017 Organic electronics Vol.50 No.-
<P><B>Abstract</B></P> <P>Recently, considerable interest have occurred in the development of an organic-inorganic-based bio-hybrid photodiodes (Bio-HPDs) with metal-free, eco-friendly, and cost-competitive features for light-sensitive devices. This paper reports a bio-inspired optical absorber material for the fabrication of Bio-HPDs using n-type hydrogenated amorphous silicon (a-Si:H) and a natural deoxyribonucleic acid (DNA)-cetyltrimethylammonium chloride (CTMA) biomaterial. a-Si:H is inexpensive and abundant, and DNA-CTMA is metal-free and eco-friendly. A DNA-CTMA coating on n-type a-Si:H leads to a chemically stable material with increased absorption and effective ties of dangling bonds and interface state density. Analysis results showed that the rectification ratio (RR) of the Bio-HPD is found to be 4 times higher than reference PD. This indicates that the effective RR is improved by the DNA-CTMA layer since it creates molecular charge interactions between DNA-CTMA layer and a-Si:H substrate. Moreover, Bio-HPD shows a light photosensitivity (I<SUB>photo</SUB>/I<SUB>dark</SUB>) of 474 with more reliable and has longer life time. In addition, the formation and feasible charge transport mechanisms are discussed. This biomaterial can be used for the development of commercially viable and environmentally safe large-scale Bio-HPDs applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High-contrast DNA-CTMA/a-Si:H bio hybrid light-sensitive device fabricated. </LI> <LI> The photodiode parameters investigated by I–V measurements. </LI> <LI> XPS and XRD structural properties were examined. </LI> <LI> FTIR, Raman and UV–Vis measurements were used. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Reddy, M. S.,Puneetha, P.,Reddy, V. R.,Lee, J. H.,Jeong, S. H.,Park, C. Springer Science + Business Media 2016 Journal of electronic materials Vol.45 No.11
<P>The temperature-dependent electrical properties and carrier transport mechanisms of tetramethylammonium hydroxide (TMAH)-treated Ni/Au/Al2O3/GaN metal-insulator-semiconductor (MIS) diodes have been investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The experimental results reveal that the barrier height (I-V) increases whereas the ideality factor decreases with increasing temperature. The TMAH-treated Ni/Au/Al2O3/GaN MIS diode showed nonideal behaviors which indicate the presence of a nonuniform distribution of interface states (N (SS)) and effect of series resistance (R (S)). The obtained R (S) and N (SS) were found to decrease with increasing temperature. Furthermore, it was found that different transport mechanisms dominated in the TMAH-treated Ni/Au/Al2O3/GaN MIS diode. At 150 K to 250 K, Poole-Frenkel emission (PFE) was found to be responsible for the reverse leakage, while Schottky emission (SE) was the dominant mechanism at high electric fields in the temperature range from 300 K to 400 K. Feasible energy band diagrams and possible carrier transport mechanisms for the TMAH-treated Ni/Au/Al2O3/GaN MIS diode are discussed based on PFE and SE.</P>
M. Siva Pratap Reddy,Peddathimula Puneetha,이영웅,정성훈,박진호 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.1
Inthis work, a deoxyribonucleic acid-cetyltrimethylammoniumchloride (DNA-CTMA) biomaterial based p-type hydrogenatedamorphous silicon (a-Si:H) photodiode (PD) is fabricated and itselectrical characteristics are investigated. The Al/DNA-CTMA/p-type a-Si:H PD parameters are studied using current-voltage (I-V), capacitancevoltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f)measurements. The barrier height and the ideality factor of the diode arefound to be 0.78 eV and 1.9, respectively. The electrical andphotoconductivity properties of the diode are analyzed by using dark I-Vand transient photocurrent techniques. The C-V-f and G/ω-V-fmeasurements indicate that the capacitance and conductance of the diodedepend on the voltage and frequency, respectively. The experimentalresults reveal that the decreases in capacitance and the increases inconductance with an increase in frequency can be explained on the basisof interface states (NSS). Series resistance (RS) measurements areperformed on the diode and discussed here. The obtained electricalparameters confirm that the Al/DNA-CTMA/p-type a-Si:H PD can beused as an optical sensor for the development of commercial applicationsthat are environmentally benign.
Siva Pratap Reddy Mallem,Peddathimmula Puneetha,Kalupudi Subramanyam,Varra Rajagopal Reddy,이동연,김영래,안성진,박귀일 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.4
Cubic-structured europium (Eu) doped zinc sulfide (ZnS) nanoparticles (NPs) were prepared via refluxing at 150 °C. Absolute structural studies showed that Eu+ ions were successfully substituted into the ZnS host lattice and changed the original structure of the host. As-fabricated ZnS:Eu NPs exhibited typical red emission due to the transition of the Eu dopant in the 5d0-7f1, 5d0-7f2, 5d0-7f3, and 5d0-7f4 energy levels of the 4f orbital of the dopant. The typical diamagnetic ZnS could be converted to tunable paramagnetic as a function of Eu-doping content. These NPs were quantified for hydrogen evolution through water splitting by artificial solar spectrum. Eu doping can drastically enhance the hydrogen (H2) evolution capability of ZnS, which is higher than that of bare ZnS NPs. The causes behind these engrossing results will be revealed. These interesting properties may find applications in optoelectronics, spintronics, and H2 evolution.