S. B. Krupanidhi
Indian Institute of Science
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Featured researches published by S. B. Krupanidhi.
AIP Advances | 2013
Murali Banavoth; Sandra Dias; S. B. Krupanidhi
The thin films of Cu 2ZnSnS4 (CZTS) were grown by co-sputtering further the structural, optical and electrical properties were analyzed and confirmed the CZTS phase formation. The photo response of CZTS in near IR photodectection has been demonstrated. The detector response was measured employing both the IR lamp and IR laser illuminations. The calculated growth and decay constants were 130 m sec and 700 m sec followed by the slower components upon lamp illumination. The external quantum efficiency of 15%, responsivity of 13 AW−1 makes CZTS a suitable candidate for the IR photodectection.
Thin Solid Films | 2003
Basavaraj Angadi; P. Victor; V. M. Jali; M.T. Lagare; Ravi Kumar; S. B. Krupanidhi
The ferroelectric Pb(Zr0.53Ti0.47)O-3 (PZT) and SrBi2Ta2O9 (SBT) thin films were prepared by laser ablation technique. The dielectric analysis, capacitance-voltage, ferroelectric hysteresis and DC leakage current measurements were performed before and after 50 MeV Li3+ ion irradiation. In both thin films, the irradiation produced some amount of amorphisation, considerable degradation in the ferroelectric properties and change in DC conductivity. On irradiation of these thin films, the phase transition temperature [T-c] of PZT decreased considerably from 628 to 508 K, while SBT exhibited a broad and diffuse transition with its T-c decreased from 573 to 548 K. The capacitance-voltage curve at 100 kHz showed a double butterfly loop with a large decrease in the capacitance and switching voltage. There was decrease in the ferroelectric hysteresis loop, remanant polarisation and coercive field. After annealing at a temperature of 673 K for 10 min while PZT partially regained the ferroelectric properties, while SBT did not. The DC conductivity measurements showed a shift in the onset of non-linear conduction region in irradiated SBT. The degradation of ferroelectric properties of the irradiated thin films is attributed to the irradiation-induced partial amorphization and the pinning of the ferroelectric domains by trapped charges. The regaining of properties after annealing is attributed to the thermal annealing of the defects generated during the irradiation
Japanese Journal of Applied Physics | 2012
Mahesh Kumar; Basanta Roul; Thirumaleshwara N. Bhat; Mohana K. Rajpalke; A. T. Kalghatgi; S. B. Krupanidhi
In0.2Ga0.8N layers were directly grown on Si(111) substrate by plasma-assisted molecular beam epitaxy (PAMBE). Structural characteristics of the as-grown InGaN epilayers were evaluated high resolution X-ray diffraction and composition of InGaN was estimated from photoluminescence spectra using the standard Vegards law. High-resolution X-ray photoemission spectroscopy measurements were used to determine the band offset of wurtzite-In0.2Ga0.8N/Si(111) heterojunctions. The valence band of InGaN is found to be 2.08 +/- 0.04 eV below that of Si. The conduction band offset (CBO) of InGaN/Si heterojunction is found similar to 0.74 eV and a type-II heterojunction
IEEE Journal of the Electron Devices Society | 2015
Murali Banavoth; M. Madhuri; S. B. Krupanidhi
Thin films of CuIn1-xAlxSe2 (CIAS) were grown on the flexible 10 micrometer thin stainless steel substrates, by dc co-sputtering from the elemental cathodes, followed by annealing with modified selenization. CuInAl alloyed precursor films were selenized both by noble gas assisted Se vapor transport in a tubular furnace and vacuum evaporation of Se in an evaporation chamber. CIAS thin films were optimized for better adhesion. X-ray diffraction, scanning electron microscopy, and UV-visible absorption spectroscopy were used to characterize the selenized films. The composition of CIAS films was varied by substituting In with Al in CuInSe2 (CIS) from 0 ≤ x ≤ 0.65 (x = Al/Al+In). Lattice parameters, average crystallite sizes, and compact density of the films, decreased when compared to CIS and (112) peak shifted to higher Braggs angle, upon Al incorporation. The dislocation density and strain were found to increase with Al doping. Solar cells with SS/Mo/CIAS/CdS/iZnO:AZnO/Al configuration were fabricated and were tested for current-voltage characteristics for various `x values, under Air Mass 1.5 Global one sun illumination. The best CIAS solar cell showed the efficiency of 6.8%, with x = 0.13, Eg = 1.17 eV, fill factor 45.04, and short circuit current density Jsc 30 mA/cm2.
Advanced Materials Research | 2013
Balaji Biradar; V. M. Jali; Banavoth Murali; S. B. Krupanidhi; Ganesh Sanjeev
The effects of 8 MeV electron irradiation (with variable fluence) on the electrical and optical properties of Lithium doped Zinc oxide thin films prepared by sol-gel synthesis are reported. There is a decrease in crystallinity and crystallite size with increase in fluence, as confirmed by XRD and SEM. We observe a decrease in transmittance, band gap and refractive index, while there is an increase in the extension coefficient with the fluence. I-V measurements have shown a decrease in leakage current and interestingly, the metal-semiconductor-metal (M-S-M) device shows only the ohmic behavior after irradiation.
Applied Nanoscience | 2014
Mahesh Kumar; Mohana K. Rajpalke; Basanta Roul; Thirumaleshwara N. Bhat; S. B. Krupanidhi
InN nanorods (NRs) were grown on Si(111) substrate by plasma-assisted molecular beam epitaxy. The growth of InN NRs has been demonstrated using an electron-beam evaporated (~2xa0nm) Au layer prior to the initiation of growth. The structure and morphology of as deposited Au film, annealed at 600xa0°C, and InN NRs were investigated using X-ray photoelectron spectroscopy and scanning electron microscopy. Chemical characterization was performed with energy dispersive X-ray analysis. Single-crystalline wurtzite structure of InN NRs is verified by transmission electron microscopy. The formation process of NRs is investigated and a qualitative mechanism is proposed.
Journal of Materials Science: Materials in Electronics | 2013
Thirumaleshwara N. Bhat; Mohana K. Rajpalke; Basanta Roul; Mahesh Kumar; S. B. Krupanidhi
This report focuses on the structural and optical properties of the GaN films grown on p-Si (100) substrates along with photovoltaic characteristics of GaN/p-Si heterojunctions fabricated with substrate nitridation and in absence of substrate nitridation. The high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), Raman and photoluminescence (PL) spectroscopic studies reveal that the significant enhancement in the structural as well as in the optical properties of GaN epifilms grown with silicon nitride buffer layer when compared with the sample grown without silicon nitride buffer layer. The low temperature PL shows a free excitonic (FX) emission peak at 3.51xa0eV at the temperature of 5xa0K with a very narrow line width of 35xa0meV. Temperature dependent PL spectra follow the Varshni equation well and peak energy blue shifts by ~63xa0meV from 300 to 5 K. Raman data confirms the strain free nature and reasonably good crystallinity of the films. The GaN/p-Si heterojunctions fabricated without substrate nitridation show a superior photovoltaic performance compared to the devices fabricated in presence of substrate nitridation. The discussions have been carried out on the junction properties. Such single junction devices exhibit a promising fill factor and conversion efficiency of 23.36 and 0.12xa0%, respectively, under concentrated AM1.5 illumination.
Integrated Ferroelectrics | 2012
D. Saranya; Neena S. John; Jayanta Parui; S. B. Krupanidhi
0.85PbMg1/3Nb2/3O3–0.15PbTiO3 (0.85PMN–0.15PT) ferroelectric relaxor thin films have been deposited on La0.5Sr0.5CoO3/(111) Pt/TiO2/SiO2/Si by pulsed laser ablation by varying the oxygen partial pressures from 50 mTorr to 400 mTorr. The X-ray diffraction pattern reveals a pyrochlore free polycrystalline film. The grain morphology of the deposited films was studied using scanning electron microscopy and was found to be affected by oxygen pressure. By employing dynamic contact-electrostatic force microscopy we found that the distribution of polar nanoregions is majorly affected by oxygen pressure. Finally, the electric field induced switching in these films is discussed in terms of domain wall pinning.
Journal of Crystal Growth | 2012
Basanta Roul; Mohana K. Rajpalke; Thirumaleshwara N. Bhat; Mahesh Kumar; A. T. Kalghatgi; S. B. Krupanidhi
Thin Solid Films | 2012
Mahesh Kumar; Basanta Roul; Thirumaleshwara N. Bhat; Mohana K. Rajpalke; A. T. Kalghatgi; S. B. Krupanidhi