Timir Datta - Academia.edu (original) (raw)
Papers by Timir Datta
Applied Physics Letters, Sep 7, 1987
We report the photoconductivity spectra of CuInSe2 thin films of precisely defined compositions t... more We report the photoconductivity spectra of CuInSe2 thin films of precisely defined compositions that are required to fabricate high-efficiency CdS/CuInSe2 thin-film solar cells. The Cu-deficient, high-resistivity CuInSe2 layer is found to be much more photoconducting than the stoichiometric, low-resistivity CuInSe2. We show that the spectral dependence of the photoconductivity of the composite CuInSe2 layer is intimately related to the spectral response of the solar cells.
arXiv (Cornell University), Nov 22, 2021
It was recently shown that when a drop of Glenlivet whiskey evaporates, it leaves behind a unifor... more It was recently shown that when a drop of Glenlivet whiskey evaporates, it leaves behind a uniform deposit [PRL 116, 124501 (2016)]. We utilize this fascinating finding in the fabrication of electrochemical metallization memory (ECM) cells. The top (Ag) and bottom (Co) electrodes in our structure are separated by a layer of Glenlivet whiskey deposit (an insulator). Measurements show the device response is typical of ECM cells that involve threshold-type switching, pinched hysteresis loops, and a large difference between the high-and low-resistance states. The surface coating process used in our experiments simplifies the device fabrication and results in a biodegradable insulating layer, which may facilitate the recovery of recyclable materials at the end of the device's use.
Physica E: Low-dimensional Systems and Nanostructures
A simple and unambiguous test has been recently suggested [J. Phys. D: Applied Physics, 52, 01LT0... more A simple and unambiguous test has been recently suggested [J. Phys. D: Applied Physics, 52, 01LT01 (2018)] to check experimentally if a resistor with memory is indeed a memristor, namely a resistor whose resistance depends only on the charge that flows through it, or on the history of the voltage across it. However, although such a test would represent the litmus test for claims about memristors (in the ideal sense), it has yet to be applied widely to actual physical devices. In this paper, we experimentally apply it to a current-carrying wire interacting with a magnetic core, which was recently claimed to be a memristor (so-called 'Φ memristor') [J. Appl. Phys. 125, 054504 (2019)]. The results of our experiment demonstrate unambiguously that this 'Φ memristor' is not a memristor: it is simply an inductor with memory. This demonstration casts further doubts that ideal memristors do actually exist in nature or may be easily created in the lab.
Bulletin of the American Physical Society, 2014
Optics introduce the subject by the familiar 1-d grating formula, a[α-α i }= n x λ , here 'a' is ... more Optics introduce the subject by the familiar 1-d grating formula, a[α-α i }= n x λ , here 'a' is the grating constant and λ is wavelength. Ever since the development of precession ruling engines by Rowland, 1-dimensional optical diffraction gratings have become ubiquitous, and workhorse in optical devices. Optical cross gratings (2-d) with lines ruled in both x & y directions are treated mutatis mutandis by a pair of 1-d grating formula. In 1912, Max von Laue, Nobel Physics for 1914, proposed his three fundamental equations for 3-d, x-ray grating as: a[α-α i }= n x λ; b[ββ i }= n y λ and c[γ-γ i }= n z λ, here α, β & γ (α i , β i & γ i) are the direction cosines of the outgoing (incoming) x-ray beam. Furthermore for simplicity an orthorhombic crystal structure with lattice constants a, b & c, oriented along each Cartesian axis respectively, were assumed. However, Laue's grating theory was soon superseded by Lawrence Bragg's namesake formula 2dSin(θ) = nλ. Peter Ewald's reciprocal lattice construction demonstrated that when certain conditions, 3-d diffraction process reduces to Bragg's reflection law. We show that reflection is a generic or universal treatment for one, two or three-dimensional gratings.
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2014
Physics and Astronomy, USC, Columbia, SC 29208-In their article-Genesis of the Bohr Atom Heilbron... more Physics and Astronomy, USC, Columbia, SC 29208-In their article-Genesis of the Bohr Atom Heilbron and Kuhn asked-what suddenly turned his [Bohr's] attention, to atom models during June 1912-they were absolutely right; during the short period in question Bohr had made an unexpected change in his research activity, he has found a new interest "atom" and would soon produce a spectacularly successful theory about it in his now famous trilogy papers in the Phil Mag (1913). We researched the trilogy papers, Bohr's memorandum, his own correspondence from that time in question and activities by Moseley (Manchester), Henry and Lawrence Bragg. Our work suggests that Bohr, also at Manchester that summer, was likely to have been inspired by Laue's sensational discovery in April 1912, of X-ray interference from atoms in crystals. The three trilogy papers include sixty five distinct (numbered) references from thirty one authors. The publication dates of the cited works range from 1896 to 1913. Bohr showed an extraordinary skill in navigating thru the most important and up-to date works. Eleven of the cited authors (Bohr included, but not John Nicholson) were recognized by ten Noble prizes, six in physics and four in chemistry.
arXiv: General Physics, 2018
Optics is limited in the 'ray-approximation'-inclusion of wave properties result in addit... more Optics is limited in the 'ray-approximation'-inclusion of wave properties result in additional phenomena and applications; interferometers and diffraction gratings are two manifestations of such non-geometric, physical optics. Incidentally, the most precise measurement ever, at one part per 10^21 in the (2017) Nobel winning discovery of gravitational waves was achieved with an interferometer. Amendments to the properties of the medium promise negative refractive index meta-materials, perfect imaging, light cloaking, and other ultra-natural marvels. Attention to photon phase, correlations, statistics and wavelength independent phase shifts result in singular optics, quantum optics and anholonomy. Here we present another possibility, namely 'Arago-optics' to maximize the efficacy of a device by strategically deploying the key qualities along its perimeter. For instance, in conventional sources, waves are generated with maximum intensity at the core; whereas in an Arago...
Bulletin of the American Physical Society, 2017
Carolina-We report magneto transport studies of CVD monolayer graphene on SiO 2 /Si substrate wit... more Carolina-We report magneto transport studies of CVD monolayer graphene on SiO 2 /Si substrate with hexagonal arrays of antidots, up to 32 Tesla with temperature from 200mK to 50K. Weak localization is observed below 0.5T. Above 10T, prominent Shubnikov-de Haas oscillations are noticed. In the intermediate magnetic fields, some commensurability peaks are also observed due to cyclotron motion of carriers. From the temperature dependent amplitude of SdH oscillation and Dingle plot, the effective mass of electron is estimated as 0.0786m e , and quantum scattering time 0.016ps. Effect of antidot geometry with different radii from 50nm to 200nm and with different shapes will be reported.
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2014
Magneto-transport of carbon inverse opal structures was investigated in the magnetic field up to ... more Magneto-transport of carbon inverse opal structures was investigated in the magnetic field up to B=9.4K at various temperatures from 2K to 50K. The transverse magnetoresistance displays linear dependence on the magnetic field instead of quadratic characteristic with the increase of the field. The linear magnetoresistance (LMR) is demonstrated to be proportional to the carrier mobility. Interesting, all the MR data as a function of B/T lies in a single curve, showing a universal behavior. Due to the peculiar structures of sample, the longitudinal magnetoresistance, which is usually very small, exhibits the same value as the transverse magnetoresistance, displaying the identical universal behavior.
Bulletin of the American Physical Society, 2017
Bulletin of the American Physical Society, 2015
Bulletin of the American Physical Society, 2016
Submitted for the MAR16 Meeting of The American Physical Society Magneto Transport of Graphene Mo... more Submitted for the MAR16 Meeting of The American Physical Society Magneto Transport of Graphene Monolayer with Antidot Arrays LEI WANG, University of South Carolina, MING YIN, Benedict College, TIMIR DATTA, University of South Carolina, GODWIN MBAMALU, Benedict College, DHEYAA ALAMERI, University of South Carolina — Graphene has a significant potential for electronics application as well as in high precision resistive metrological standard. Here we report magneto transport studies of monolayer graphene with antidot in hexagonal arrays on SiO2/Si substrate. The choice of antidot array was motivated by the potential to enhance quantum interference effect amongst charge carriers. The graphene-antidot arrays were fabricated by electron beam lithography followed by reactive ion etching. In our samples the dc magnetic field (B) was applied continuously up to 18 Tesla while the measurement temperature (T) was held steady at desired set points, ranging from 200 mK to 20 K. The effect of nano...
Bulletin of the American Physical Society, 2020
Magneto-transport of carbon inverse opal structures were investigated in the 2.5 to 300 K tempera... more Magneto-transport of carbon inverse opal structures were investigated in the 2.5 to 300 K temperatures and magnetic fields in the 0-10T regime. Qualitatively, our observations lie between those reported by previous researchers. Over this temperature range, transport (in zero magnetic field) is non-metallic; the resistance decreased with rising temperature however the temperature dependent behavior is not activated, as observed with variable range hopping. In three-dimensions, such behavior can also be the result of weak localization and electron-electron interactions; in particular the change in conductivity is a polynomial in fractional powers of absolute temperature. At subhelium temperature regimes the relative magneto resistance is measured to be ∼ 0.1 percent per Tesla. Results of data analysis for several different scenarios will be reported.
Advanced Electronic Materials, 2020
It has been suggested that all resistive‐switching memory cells are memristors. The latter are hy... more It has been suggested that all resistive‐switching memory cells are memristors. The latter are hypothetical, ideal devices whose resistance, as originally formulated, depends only on the net charge that traverses them. Recently, an unambiguous test has been proposed to determine whether a given physical system is indeed a memristor or not. Here, such a test is experimentally applied to both in‐house fabricated Cu‐SiO2 and commercially available electrochemical metallization cells. The results unambiguously show that electrochemical metallization memory cells are not memristors. Since the particular resistance‐switching memories employed in the study share similar features with many other memory cells, the findings refute the claim that all resistance‐switching memories are memristors. They also cast doubts on the existence of ideal memristors as actual physical devices that can be fabricated experimentally. The results then lead to formulate two memristor impossibility conjectures r...
Spectrochimica Acta Part A: Molecular Spectroscopy, 1994
The far infrared (FT-IR) spectra of Y203, CuO, BaO,, YBa$uJ07_6 and Tl,Ca,Ba,Cu,O,,, have been re... more The far infrared (FT-IR) spectra of Y203, CuO, BaO,, YBa$uJ07_6 and Tl,Ca,Ba,Cu,O,,, have been recorded in the range of 350-60 cm-'. A variety of sample handling techniques have been utilized which include dispersion of the samples in nujol and fluorolube. Additionally, we present preliminary results of a technique of preparing thin films (l-20pm thick) of these materials. These films do not require a substrate but are dispersed in a polyethylene matrix fused between two polyethylene plates. Such films are suitable for optical applications.
Applied Physics Letters, Sep 7, 1987
We report the photoconductivity spectra of CuInSe2 thin films of precisely defined compositions t... more We report the photoconductivity spectra of CuInSe2 thin films of precisely defined compositions that are required to fabricate high-efficiency CdS/CuInSe2 thin-film solar cells. The Cu-deficient, high-resistivity CuInSe2 layer is found to be much more photoconducting than the stoichiometric, low-resistivity CuInSe2. We show that the spectral dependence of the photoconductivity of the composite CuInSe2 layer is intimately related to the spectral response of the solar cells.
arXiv (Cornell University), Nov 22, 2021
It was recently shown that when a drop of Glenlivet whiskey evaporates, it leaves behind a unifor... more It was recently shown that when a drop of Glenlivet whiskey evaporates, it leaves behind a uniform deposit [PRL 116, 124501 (2016)]. We utilize this fascinating finding in the fabrication of electrochemical metallization memory (ECM) cells. The top (Ag) and bottom (Co) electrodes in our structure are separated by a layer of Glenlivet whiskey deposit (an insulator). Measurements show the device response is typical of ECM cells that involve threshold-type switching, pinched hysteresis loops, and a large difference between the high-and low-resistance states. The surface coating process used in our experiments simplifies the device fabrication and results in a biodegradable insulating layer, which may facilitate the recovery of recyclable materials at the end of the device's use.
Physica E: Low-dimensional Systems and Nanostructures
A simple and unambiguous test has been recently suggested [J. Phys. D: Applied Physics, 52, 01LT0... more A simple and unambiguous test has been recently suggested [J. Phys. D: Applied Physics, 52, 01LT01 (2018)] to check experimentally if a resistor with memory is indeed a memristor, namely a resistor whose resistance depends only on the charge that flows through it, or on the history of the voltage across it. However, although such a test would represent the litmus test for claims about memristors (in the ideal sense), it has yet to be applied widely to actual physical devices. In this paper, we experimentally apply it to a current-carrying wire interacting with a magnetic core, which was recently claimed to be a memristor (so-called 'Φ memristor') [J. Appl. Phys. 125, 054504 (2019)]. The results of our experiment demonstrate unambiguously that this 'Φ memristor' is not a memristor: it is simply an inductor with memory. This demonstration casts further doubts that ideal memristors do actually exist in nature or may be easily created in the lab.
Bulletin of the American Physical Society, 2014
Optics introduce the subject by the familiar 1-d grating formula, a[α-α i }= n x λ , here 'a' is ... more Optics introduce the subject by the familiar 1-d grating formula, a[α-α i }= n x λ , here 'a' is the grating constant and λ is wavelength. Ever since the development of precession ruling engines by Rowland, 1-dimensional optical diffraction gratings have become ubiquitous, and workhorse in optical devices. Optical cross gratings (2-d) with lines ruled in both x & y directions are treated mutatis mutandis by a pair of 1-d grating formula. In 1912, Max von Laue, Nobel Physics for 1914, proposed his three fundamental equations for 3-d, x-ray grating as: a[α-α i }= n x λ; b[ββ i }= n y λ and c[γ-γ i }= n z λ, here α, β & γ (α i , β i & γ i) are the direction cosines of the outgoing (incoming) x-ray beam. Furthermore for simplicity an orthorhombic crystal structure with lattice constants a, b & c, oriented along each Cartesian axis respectively, were assumed. However, Laue's grating theory was soon superseded by Lawrence Bragg's namesake formula 2dSin(θ) = nλ. Peter Ewald's reciprocal lattice construction demonstrated that when certain conditions, 3-d diffraction process reduces to Bragg's reflection law. We show that reflection is a generic or universal treatment for one, two or three-dimensional gratings.
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2014
Physics and Astronomy, USC, Columbia, SC 29208-In their article-Genesis of the Bohr Atom Heilbron... more Physics and Astronomy, USC, Columbia, SC 29208-In their article-Genesis of the Bohr Atom Heilbron and Kuhn asked-what suddenly turned his [Bohr's] attention, to atom models during June 1912-they were absolutely right; during the short period in question Bohr had made an unexpected change in his research activity, he has found a new interest "atom" and would soon produce a spectacularly successful theory about it in his now famous trilogy papers in the Phil Mag (1913). We researched the trilogy papers, Bohr's memorandum, his own correspondence from that time in question and activities by Moseley (Manchester), Henry and Lawrence Bragg. Our work suggests that Bohr, also at Manchester that summer, was likely to have been inspired by Laue's sensational discovery in April 1912, of X-ray interference from atoms in crystals. The three trilogy papers include sixty five distinct (numbered) references from thirty one authors. The publication dates of the cited works range from 1896 to 1913. Bohr showed an extraordinary skill in navigating thru the most important and up-to date works. Eleven of the cited authors (Bohr included, but not John Nicholson) were recognized by ten Noble prizes, six in physics and four in chemistry.
arXiv: General Physics, 2018
Optics is limited in the 'ray-approximation'-inclusion of wave properties result in addit... more Optics is limited in the 'ray-approximation'-inclusion of wave properties result in additional phenomena and applications; interferometers and diffraction gratings are two manifestations of such non-geometric, physical optics. Incidentally, the most precise measurement ever, at one part per 10^21 in the (2017) Nobel winning discovery of gravitational waves was achieved with an interferometer. Amendments to the properties of the medium promise negative refractive index meta-materials, perfect imaging, light cloaking, and other ultra-natural marvels. Attention to photon phase, correlations, statistics and wavelength independent phase shifts result in singular optics, quantum optics and anholonomy. Here we present another possibility, namely 'Arago-optics' to maximize the efficacy of a device by strategically deploying the key qualities along its perimeter. For instance, in conventional sources, waves are generated with maximum intensity at the core; whereas in an Arago...
Bulletin of the American Physical Society, 2017
Carolina-We report magneto transport studies of CVD monolayer graphene on SiO 2 /Si substrate wit... more Carolina-We report magneto transport studies of CVD monolayer graphene on SiO 2 /Si substrate with hexagonal arrays of antidots, up to 32 Tesla with temperature from 200mK to 50K. Weak localization is observed below 0.5T. Above 10T, prominent Shubnikov-de Haas oscillations are noticed. In the intermediate magnetic fields, some commensurability peaks are also observed due to cyclotron motion of carriers. From the temperature dependent amplitude of SdH oscillation and Dingle plot, the effective mass of electron is estimated as 0.0786m e , and quantum scattering time 0.016ps. Effect of antidot geometry with different radii from 50nm to 200nm and with different shapes will be reported.
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2014
Magneto-transport of carbon inverse opal structures was investigated in the magnetic field up to ... more Magneto-transport of carbon inverse opal structures was investigated in the magnetic field up to B=9.4K at various temperatures from 2K to 50K. The transverse magnetoresistance displays linear dependence on the magnetic field instead of quadratic characteristic with the increase of the field. The linear magnetoresistance (LMR) is demonstrated to be proportional to the carrier mobility. Interesting, all the MR data as a function of B/T lies in a single curve, showing a universal behavior. Due to the peculiar structures of sample, the longitudinal magnetoresistance, which is usually very small, exhibits the same value as the transverse magnetoresistance, displaying the identical universal behavior.
Bulletin of the American Physical Society, 2017
Bulletin of the American Physical Society, 2015
Bulletin of the American Physical Society, 2016
Submitted for the MAR16 Meeting of The American Physical Society Magneto Transport of Graphene Mo... more Submitted for the MAR16 Meeting of The American Physical Society Magneto Transport of Graphene Monolayer with Antidot Arrays LEI WANG, University of South Carolina, MING YIN, Benedict College, TIMIR DATTA, University of South Carolina, GODWIN MBAMALU, Benedict College, DHEYAA ALAMERI, University of South Carolina — Graphene has a significant potential for electronics application as well as in high precision resistive metrological standard. Here we report magneto transport studies of monolayer graphene with antidot in hexagonal arrays on SiO2/Si substrate. The choice of antidot array was motivated by the potential to enhance quantum interference effect amongst charge carriers. The graphene-antidot arrays were fabricated by electron beam lithography followed by reactive ion etching. In our samples the dc magnetic field (B) was applied continuously up to 18 Tesla while the measurement temperature (T) was held steady at desired set points, ranging from 200 mK to 20 K. The effect of nano...
Bulletin of the American Physical Society, 2020
Magneto-transport of carbon inverse opal structures were investigated in the 2.5 to 300 K tempera... more Magneto-transport of carbon inverse opal structures were investigated in the 2.5 to 300 K temperatures and magnetic fields in the 0-10T regime. Qualitatively, our observations lie between those reported by previous researchers. Over this temperature range, transport (in zero magnetic field) is non-metallic; the resistance decreased with rising temperature however the temperature dependent behavior is not activated, as observed with variable range hopping. In three-dimensions, such behavior can also be the result of weak localization and electron-electron interactions; in particular the change in conductivity is a polynomial in fractional powers of absolute temperature. At subhelium temperature regimes the relative magneto resistance is measured to be ∼ 0.1 percent per Tesla. Results of data analysis for several different scenarios will be reported.
Advanced Electronic Materials, 2020
It has been suggested that all resistive‐switching memory cells are memristors. The latter are hy... more It has been suggested that all resistive‐switching memory cells are memristors. The latter are hypothetical, ideal devices whose resistance, as originally formulated, depends only on the net charge that traverses them. Recently, an unambiguous test has been proposed to determine whether a given physical system is indeed a memristor or not. Here, such a test is experimentally applied to both in‐house fabricated Cu‐SiO2 and commercially available electrochemical metallization cells. The results unambiguously show that electrochemical metallization memory cells are not memristors. Since the particular resistance‐switching memories employed in the study share similar features with many other memory cells, the findings refute the claim that all resistance‐switching memories are memristors. They also cast doubts on the existence of ideal memristors as actual physical devices that can be fabricated experimentally. The results then lead to formulate two memristor impossibility conjectures r...
Spectrochimica Acta Part A: Molecular Spectroscopy, 1994
The far infrared (FT-IR) spectra of Y203, CuO, BaO,, YBa$uJ07_6 and Tl,Ca,Ba,Cu,O,,, have been re... more The far infrared (FT-IR) spectra of Y203, CuO, BaO,, YBa$uJ07_6 and Tl,Ca,Ba,Cu,O,,, have been recorded in the range of 350-60 cm-'. A variety of sample handling techniques have been utilized which include dispersion of the samples in nujol and fluorolube. Additionally, we present preliminary results of a technique of preparing thin films (l-20pm thick) of these materials. These films do not require a substrate but are dispersed in a polyethylene matrix fused between two polyethylene plates. Such films are suitable for optical applications.