THE GRAPHENE-SiC SUBSTRATE INTERACTION ENHANCED NEAR-INFRARED ABSORPTION

When epitaxially grown on silicon carbide, a single layer graphene will exhibit a finite energy bandgap like a conventional semiconductor, and its energy dispersion is no longer linear in momentum space in the low energy regime. In this paper, we present a quantitative analysis on the effect of the SiC substrate in the optical absorption of π-electrons in graphene. We calculated the absorption matrix element and the optical absorption in the near infrared even to the visible region by taking into account the SiC substrate effect. It has been found that the substrate effect can significantly enhance the optical absorption in graphene in the near-infrared region, even by up to 90%. It may be helpful to eliminate the previous discrepancy of optical transmission between the theoretical results and the experimental results in the near-infrared to the visible region.

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Well-Aligned Graphene Oxide Nanosheets Decorated with Zinc Oxide Nanocrystals for High Performance Photocatalytic Application

International Journal of Nanoscience ◽

10.1142/s0219581x15500076 ◽

2015 ◽

Vol 14 (03) ◽

pp. 1550007 ◽

Cited By ~ 53

Author(s):

K. Kaviyarasu ◽

C. Maria Magdalane ◽

E. Manikandan ◽

M. Jayachandran ◽

R. Ladchumananandasivam ◽

...

Keyword(s):

Zinc Oxide ◽

Graphene Oxide ◽

High Performance ◽

Chemical Reduction ◽

Visible Region ◽

Single Layer ◽

Single Layer Graphene ◽

Graphene Oxides ◽

X Ray ◽

Nanoscale Structures

Graphene oxide (GO) nanosheets modified with zinc oxide nanocrystals were achieved by a green wet-chemical approach. As-obtained products were characterized by XRD, Raman spectra, XPS, HR-TEM, EDS, PL and Photocatalytic studies. XRD studies indicate that the GO nanosheet have the same crystal structure found in hexagonal form of ZnO . The enhanced Raman spectrum of 2D bands confirmed formation of single layer graphene oxides. The gradual photocatalytic reduction of the GO nanosheet in the GO : ZnO suspension of ethanol was studied by using X-ray photoelectron (XPS) spectroscopy. The nanoscale structures were observed and confirmed using high resolution transmission electron microscopy (HR-TEM). The evolution of the elemental composition, especially the various numbers of layers were determined from energy dispersive X-ray spectra (EDS). PL properties of GO : ZnO nanosheet were found to be dependent on the growth condition and the resultant morphology revealed that GO nanosheet were highly transparent in the visible region. The photocatalytic performance of GO : ZnO nanocomposites was performed under UV irradiation. Therefore, the ZnO nanocrystals in the GO : ZnO composite could be applied in gradual chemical reduction and consequently tuning the electrical conductivity of the graphene oxide nanosheet.

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Optical absorption of rare-earth-doped BeF2 glasses

Journal of Materials Research ◽

10.1557/jmr.1986.0139 ◽

1986 ◽

Vol 1 (1) ◽

pp. 139-143

Author(s):

P. A. Tick

Keyword(s):

Optical Absorption ◽

Rare Earths ◽

Near Infrared ◽

Light Transmission ◽

Infrared Region ◽

Optical Absorption Spectra ◽

Intrinsic Attenuation ◽

Optimum Wavelength ◽

Near Infrared Region ◽

Rare Earth Doped

BeF2 glasses are potentially useful materials for light transmission in the near infrared region of the spectrum. While the intrinsic attenuation of BeF2 is thought to be much lower than silica, the optimum wavelength will be further in the infrared, near 2.1 μ. In this spectral region impurities other than transition metals may be important—rare earths, for example. The data required to estimate the contributions to attenuation are normally not available; hence it is the purpose of the present work to provide that information. Using a binary BeF2/ThF4 glass, the optical absorption spectra of a number of rare earths are measured. The experimental procedures, optical spectra, and absorption strength are described.

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Nanoprinted high-neuron-density optical linear perceptrons performing near-infrared inference on a CMOS chip

Light Science & Applications ◽

10.1038/s41377-021-00483-z ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Elena Goi ◽

Xi Chen ◽

Qiming Zhang ◽

Benjamin P. Cumming ◽

Steffen Schoenhardt ◽

...

Keyword(s):

Machine Learning ◽

High Speed ◽

Near Infrared ◽

Single Layer ◽

Infrared Region ◽

Optical Devices ◽

Medical Diagnostics ◽

Oxide Semiconductor ◽

Process Data ◽

Neuron Density

AbstractOptical machine learning has emerged as an important research area that, by leveraging the advantages inherent to optical signals, such as parallelism and high speed, paves the way for a future where optical hardware can process data at the speed of light. In this work, we present such optical devices for data processing in the form of single-layer nanoscale holographic perceptrons trained to perform optical inference tasks. We experimentally show the functionality of these passive optical devices in the example of decryptors trained to perform optical inference of single or whole classes of keys through symmetric and asymmetric decryption. The decryptors, designed for operation in the near-infrared region, are nanoprinted on complementary metal-oxide–semiconductor chips by galvo-dithered two-photon nanolithography with axial nanostepping of 10 nm1,2, achieving a neuron density of >500 million neurons per square centimetre. This power-efficient commixture of machine learning and on-chip integration may have a transformative impact on optical decryption3, sensing4, medical diagnostics5 and computing6,7.

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Design and fabrication of a semi-transparent solar cell considering the effect of the layer thickness of MoO3/Ag/MoO3 transparent top contact on optical and electrical properties

Scientific Reports ◽

10.1038/s41598-021-92539-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Çağlar Çetinkaya ◽

Erman Çokduygulular ◽

Barış Kınacı ◽

Feyza Güzelçimen ◽

Yunus Özen ◽

...

Keyword(s):

Solar Cell ◽

Layer Thickness ◽

High Performance ◽

Near Infrared ◽

Visible Region ◽

Infrared Region ◽

Experimental Comparison ◽

Top Contact ◽

Cie Chromaticity ◽

Design And Manufacture

AbstractWe conducted the present study to design and manufacture a semi-transparent organic solar cell (ST-OSC). First, we formed a transparent top contact as MoO3/Ag/MoO3 in a dielectric/metal/dielectric (DMD) structure. We performed the production of an FTO/ZnO/P3HT:PCBM/MoO3/Ag/MoO3 ST-OSC by integrating MoO3/Ag/MoO3 (10/$$d_{m}$$ d m /$$d_{{od}}$$ d od nm) instead of an Ag electrode in an opaque FTO/ZnO/P3HT:PCBM/MoO3/Ag (–/40/130/10/100 nm) OSC, after theoretically achieving optimal values of optical and electrical parameters depending on Ag layer thickness. The transparency decreased with the increase of $$d_{m}$$ d m values for current DMD. Meanwhile, maximum transmittance and average visible transmittance (AVT) indicated the maximum values of over 92% for $$d_{m} ~$$ d m = 4 and 8 nm, respectively. For ST-OSCs, the absorption and reflectance increased in the visible region by a wavelength of longer than 560 nm and in the whole near-infrared region by increasing $$d_{m}$$ d m up to 16 nm. Moreover, in the CIE chromaticity diagram, we reported a shift towards the D65 Planckian locus for colour coordinates of current ST-OSCs. Electrical analysis indicated the photogenerated current density and AVT values for $$d_{m} = 6$$ d m = 6 nm as 63.30 mA/cm2 and 38.52%, respectively. Thus, the theoretical and experimental comparison of optical and electrical characteristics confirmed that the manufactured structure is potentially conducive for a high-performance ST-OSC.

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ANÁLISIS DE COMPONENTES PRINCIPALES DE IMÁGENES MULTIESPECTRALES EN EL ÁMBITO DEL ARTE RUPESTRE

Proceedings - 1st Congress in Geomatics Engineering - CIGeo ◽

10.4995/cigeo2017.2017.6597 ◽

2017 ◽

Author(s):

Berta Carrión-Ruiz ◽

José Luis Lerma

Keyword(s):

Principal Component Analysis ◽

Near Infrared ◽

Rock Art ◽

Visible Region ◽

Principal Component ◽

Optical Filters ◽

Infrared Region ◽

Spectral Behaviour ◽

Near Infrared Region ◽

Art Analysis

This paper tackles principal component analysis (PCA) in images that include wavelengths between 380-1000 nm. Our approach is focussed on taking advantage of the potencial of ultraviolet and infrarred images, in combination with the visible ones, to improve documentation process and rock art analysis. In this way, we want to improve the discrimination between pigment and support rock, and analyse the spectral behaviour of rock art paintings in the ultraviolet and infrared regions. Three images were used, one image from the ultraviolet (UV) region, one from the visible region (VIS) and another one from the near infrared region (NIR). Optical filters coupled to the camera optics were used to take the images. These filters capture specific wavelengths excluding radiation that we are not interested in registering. Finally, PCA is applied to the acquired images. The results obtained demonstrate the PCA usefulness with imagery in this field and also it is possible to extract some conclusions about the correspondent paint pigments.http://dx.doi.org/10.4995/CIGeo2017.2017.6597

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CHLOROPHYLL ANALYSIS OF WHOLE RAPESEED KERNELS BY NEAR INFRARED REFLECTANCE

Canadian Journal of Plant Science ◽

10.4141/cjps82-131 ◽

1982 ◽

Vol 62 (4) ◽

pp. 875-884 ◽

Cited By ~ 20

Author(s):

RUSSELL TKACHUK ◽

F. D. KUZINA

Keyword(s):

Chlorophyll Content ◽

Near Infrared ◽

Good Accuracy ◽

Visible Region ◽

Infrared Region ◽

Multiple Correlation Coefficient ◽

Multiple Correlation ◽

Near Infrared Reflectance ◽

Laboratory Results ◽

Near Infrared Region

Chlorophyll content was determined in whole rapeseed samples, from Regent and Candle cultivars, by using a reflectance technique in the visible and near infrared region. Chlorophyll content was estimated with good accuracy when predicted results for 42 samples of Regent, 37 samples of Candle and 79 samples for both cultivars combined were compared with standard laboratory results. For Regent, a multiple correlation coefficient (R) of 0.944 and a standard error of estimate (Sy) of 4.7 were obtained when reflectance was measured at six wavelengths. For Candle, R = 0.963 and Sy = 4.4, using another six wavelengths. For both cultivars combined, R = 0.939 and Sy = 4.8, again using a different set of six wavelengths. Wavelengths for predicting chlorophyll were selected from the 630-to 754-nm visible region, and from the 1640- to 2176-nm near infrared region. This reflectance method described for whole rapeseed is rapid, involves no sample preparation, and leaves the seed intact and available for other uses.

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Optical properties of spray pyrolysis deposited Cds:Al thin films

Journal of Bangladesh Academy of Sciences ◽

10.3329/jbas.v39i1.23654 ◽

2015 ◽

Vol 39 (1) ◽

pp. 25-30 ◽

Cited By ~ 2

Author(s):

A Hasnat Rubel ◽

J Podder

Keyword(s):

Thin Films ◽

Optical Properties ◽

Spray Pyrolysis ◽

Near Infrared ◽

Visible Region ◽

Cadmium Sulphide ◽

Infrared Region ◽

Photo Detectors ◽

Direct Energy ◽

Academy Of Sciences

Aluminium doped cadmium sulphide thin films were prepared on glass substrate using aqueous solution of cadmium sulphide and thiourea salts by spray pyrolysis deposition (SPD) technique. Its optical properties were analyzed as a function of doping concentration. The direct energy band-gap of Al-doped CdS films was estimated in the range of 2.25 to 2.48 eV. The optical spectra of Cd1-xAlxS ternary system exhibit high absorption near visible region and transmission throughout the near-infrared region (600 - 1200 nm). Thus so obtained hetero-junction films are suitable for fabrication of photo detectors, solar cells and other optoelectronics devices.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 25-30, 2015

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