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Light–matter interaction in graphene can be engineered and substantially enhanced through plasmonic sensitization, which has led to numerous applications in photodetection, sensing, photocatalysis and spectroscopy. The majority of these designs have relied on conventional plasmonic materials such as gold, silver and aluminum. This limits the implementation of such devices to the ultraviolet and visible regimes of the electromagnetic spectrum. However, for many practical applications, including those relevant to security and defense, the development of new strategies and materials for sensing and detection of infra red (IR) light is crucial. Here we use surface enhanced Raman spectroscopy (SERS), for direct visualization and estimation of enhanced light–matter interaction in graphene in the mid-IR regime, through sensitization by an unconventional plasmonic material. Specifically, we fabricate a hybrid device consisting of a single layer graphene and a two-dimensional array of nanodiscs of aluminum doped zinc oxide (AZO), which is a highly doped semiconductor, exhibiting plasmonic resonance in the mid-IR. We find that the enhancement in the SERS signal of graphene is of similar magnitude to what has been achieved previously in the visible using conventional plasmonic materials. Our results establish the potential of such hybrid systems for graphene-based optical and optoelectronic applications in the mid-IR.

We have investigated the electronic structure and optical properties of zinc molybdenum oxide (Zn2Mo3O8) by using both first-principle calculations and experiments. Optical properties of this material is very similar to other ternary oxides of tetravalent molybdenum (A2Mo3O8: A = Mg, Fe, Cd); therefore, this study provides meaningful insight into optical properties and possible phtotovoltaic applicability of these class of metal oxide cluster compounds. We use state-of-the-art methods, based on density functional theory and the GW approximation to the self-energy, to obtain the quasiparticle band structure and absorption spectra of the material. Our calculations shows that Zn2Mo3O8 is a near indirect gap semiconductor with an indirect gap of 3.14 eV. The direct gap of the material is 3.16 eV. We also calculate the optical absorption in the material. Calculated results compare well with UV–visible spectroscopy and spectroscopic ellipsometry measurements done on polycrystalline thin films of Zn2Mo3O8. We sh...

Metal-oxide/silicon carrier-selective heterojunctions may be a low-cost high-efficiency alternative to conventional silicon solar cells. Here, a passivated Si/cuprous oxide (Cu2O) hole-selective heterojunction with high open-circuit voltage ( V OC) is reported. Cu2O is abundant, nontoxic, and can be deposited at low temperatures and potentially at low cost. The Si/Cu2O heterojunction has a large conduction band offset of 0.9 eV and a negligible valence band offset, which blocks the transport of electrons but allows the transport of holes. The as-deposited hetero-interface is limited due to a high density of defects. However, the interface defect density can be reduced by a 1.2 nm thin tunneling SiO2 layer, which enables the realization of a Si/Cu2O heterojunction solar cell with an open-circuit voltage ( V OC) of 0.528 V, a 200 mV improvement over the state-of-the-art.

The ability to control the conductivity and carrier concentration in a semiconducting material is paramount to making electronic devices using it. Few metal oxides are known whose conductivity can be easily modulated across a wide range to suit device requirements. In this work, thin films of manganese vanadium oxide (MVO) are deposited using pulsed laser deposition. The ability to vary the conductivity of MVO over five orders of magnitude, by varying the deposition pressure, has been demonstrated. The effect of variation of deposition on the responsivity of metal-semiconductor-metal structures is also reported. Using ‘highly doped’ and ‘moderately doped’ MVO, solar cells are demonstrated.

The lack of techniques for counter doping in two dimensional (2D) semiconductors has hindered the development of p/n junctions, which are the basic building blocks of electronic devices. In this work, low-energy argon ions are used to create sulfur vacancies and are subsequently ``filled'' with oxygen to create p-doped MoS2-xOx. The incorporation of oxygen into the MoS2 lattice and hence band-structure modification reveal the nature of the p-type doping. These changes are validated by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Raman spectroscopy, and photoluminescence measurements combined with density functional theory calculations. Electrical measurements reveal a complete flip in carrier polarity from n-type to p-type, which is further examined using temperature-dependent transport measurements. The enhancement of p-field-effect transistor characteristics is facilitated by employing top-gated transistors and area-selective vacancy engineering only in the contact regions. Finally, on the same flake, an in-plane MoS2 (n)/MoS2-xOx (p) type-I (straddling) heterojunction with rectifying behavior and excellent broadband photoresponse is demonstrated and explained using band diagrams. The spatial/metallurgical abruptness (

Semiconducting oxides are often stable, non-toxic, and can potentially be deposited at a low cost. The existence of oxides with appropriate bandgap (2V2O7, MVO). Films deposited using pulsed laser deposition show no photoluminescence (PL). After annealing in a nitrogen ambience, sharp PL (FWHM ∼ 100 µeV) peaks are observed at low temperatures, which indicates improved optoelectronic quality. Our analysis suggests these emissions are from carriers trapped in very shallow native acceptor and donor type defects. This improvement is correlated with the reduction in Urbach energy, which also suggests reduced electronic disorder. Coupled with low bandgap and easy processing, MVO seems to be an exciting material for optoelectronics and photovoltaics.

Semiconducting metal oxides are attractive for various applications since most oxides are non-toxic, stable, and easy to deposit. Wide band-gap materials have been studied more extensively, compared to low bandgap materials, which introduces limitations to the applications of oxides. Study of low band-gap semiconducting oxides can propel the usage of oxides in a wider range of applications. Here, the electronic, structural, and optical properties of Zn2Mo3O8 (ZMO) are investigated. Stoichiometric polycrystalline films of ZMO are deposited using pulsed laser deposition system at room temperature. The unintentionally n-doped films show a hall electron mobility of 0.7 cm2 V−1 s−1 and have a bandgap of 2.1 eV. The photoelectron spectra contain complex peak profiles which are explained to be a manifestation of final state effects. The orbital contribution to the valence band of ZMO is probed using resonant photoelectron spectroscopy, which confirms that the valence band is composed of Mo 4d levels. The conduction and valence band edges are predicted to be at 4.2 eV and 6.3 eV, so most of the conventional wide band-gap oxides can be used as hole-blocking layers with ZMO. Under A.M. 1.5 illumination, single-sided Schottky diode with Fluorine-doped tin oxide/TiO2/ZMO/Au structure shows no photovoltaic action, possibly due to high exciton binding energy and low carrier drift lengths. However, the Schottky device shows a higher current under illumination, which suggests that with improvement in carrier drift lengths, ZMO can find applications in low-cost optoelectronic devices on flexible substrates like plastic or Polyethylene terephthalate.

We report silver-chromate $\mathrm{(Ag_{2}CrO_{4}, ACO)}$ as absorber for all-oxide photovoltaics. ACO is known for photocatalysts, but this is the first demonstration of a solar cell using ACO as the absorber. ACO is deposited using pulsed laser deposition. Material characterization shows that under optimum conditions, high-quality polycrystalline films of ACO can be deposited. Schottky junction device with a lateral Al/ACO/Au structure shows diode-like characteristics with an ON/OFF ratio of $> 1000.$ Under AM1.5 illumination, the unoptimized cell shows an open circuit voltage of 0.2 V, which is significant for all-oxide photovoltaics.

We present a silicon/oxide heterojunction solar cell using a doped-Cu 2 O electron blocking layer. Surface recombination velocity shows that doped-Cu 2 O provides better passivation for the surface defects in silicon than undoped Cu 2 O. More importantly, the built-in field at the Cu 2 O/Si interface is higher with the doped Cu 2 O. The higher field allows the doped-Cu 2 O/Si solar cells to attain an open-circuit voltage (VOC) of 0.45V, better than 0.32V previously reported [1]. Integrating a transparent top electrode with the Cu 2 O/Si solar cells, reduces optical transmission losses and increases the short-circuit current density (JSC) from 14.3 mA/cm2 to 17.9 mA/cm2. Overall doped-Cu 2 O/Si heterojunction solar cells show a power-conversion efficiency (PCE) of 5.23%.

All-oxide solar cells are attractive due to their stability, low cost and ease of fabrication. Very few oxide-absorbers are known and the efficiencies are limited by low mobility and lifetimes. In this work, for the first time, photovoltaic properties of a new oxide semiconductor, Mn2V207 (MVO) are described. Optical measurements show that MVO has an indirect bandgap of 1.6 eV and a direct bandgap of 1.75 eV, which suggests that it absorbs efficiently in the visible region of the solar spectrum. The valence and conduction band positions of the intrinsically n-doped MVO film are determined to be at 5.5 eV and 3.9 eV. Schottky solar cells fabricated using Pt/MVO heterojunction show low short circuit current (Jsc) and open circuit voltage (Voc). Annealing in nitrogen ambience results in a Jsc of 0.46 mA/cm2 a 50x increase and of Voc 0.21 V, almost 10x increase compared to un-annealed device. A maximum power of 24.1 μcm2is obtained, which is two orders of magnitude higher than un-annealed devices.

Metal-oxide semiconductors are attractive as solar absorbers because they are abundant, stable, environmentally-safe, and low-cost. This work reports the electronic and optical properties of Zn2M030s (ZMO), a novel oxide-based solar absorber. ZMO has a direct bandgap of 1.9-2.1 eV, so it can efficiently absorb visible photons. As-deposited films are polycrystalline and unintentionally doped n-type with $\sim 10^{17}\mathrm{cm}^{-3}$ carriers. Electron mobility of $0.6-0.7 \mathrm{cm}^{2}/\mathrm{V}-\mathrm{s}$ is comparable to other thin-film absorbers like CdTe. The conduction and valence band edges in ZMO are 4.4 eV and 6.3 eV below vacuum level, respectively. Preliminary devices show photoconductivity with a 1. $5\mathrm{x}$ increase in current upon illumination

Today is an age of Big data. Big data is the normally unstructured data. Apache Hive is largely used for analysis in process of huge data. Because it is like SQL so easy to get analytical report. The main problem is that unstructured data loading and storage as well as Fast and timely analysis of large amount of data. There are data Compression columnar format like ORC(Optimized Row And Columnar) and Parquet columnar format. In this paper we used USGS (United States Geological Survey) Earthquake dataset. USGS provides the multi-Dimension dataset of earthquake of every day, week and month. We applied hadoop Hive's ORC format On monthly USGS earthquake dataset. ORC format Stored dataset efficiently without lose so that the most important data without losing stored on HDFS. We compare result of ORC Sorted and Unsorted dataset on the basses of time required to load the dataset on HDFS.