Crystallographic and optical properties of wide bandgap photovoltaic semiconductor system, Cu(Al,In)Se2

2022 ◽  
Author(s):  
Ryoma Yoneda ◽  
Kosuke Beppu ◽  
Tsuyoshi Maeda ◽  
Takahiro Wada
Keyword(s):  
Energy Levels ◽  
Valence Band Maximum ◽  
Band Gap Energy ◽  
Wide Bandgap ◽  
Bandgap Energy ◽  
Al Content ◽  
Local Structures ◽  
Optical And Electronic Properties ◽  
Crystallographic Characteristics ◽  
X Ray Absorption

Abstract We characterized the optical and electronic properties of chalcopyrite-type Cu(Al,In)Se2, which is a candidate for wide-bandgap solar cell materials. The bandgap energy was determined from diffuse reflectance spectra. The band gap energy increased from 1.00 eV for CuInSe2 to 2.61 eV for CuAlSe2 with an increase in the Al content. The ionization energy corresponding to the energy levels of the valence band maximum (VBM) was determined using photoemission yield spectroscopy (PYS). The VBM level of the Cu(Al,In)Se2 system stayed relatively constant, but the conduction band minimum (CBM) level increased with increasing Al content. To analyze the local structures of Cu and In atoms in Cu(Al,In)Se2, Cu and In K-edge X-ray absorption fine structure (XAFS) spectra were measured at SPring-8. We discuss the crystallographic characteristics of Cu(Al,In)Se2 based on the results of the XAFS analyses and a comparison of the phase diagrams of the Cu2Se-Al2Se3, Cu2Se-In2Se3, and Cu2Se-Ga2Se3 systems.

scholarly journals A Review of the Synthesis, Properties, and Applications of Bulk and Two-Dimensional Tin (II) Sulfide (SnS)

2021 ◽  
Vol 11 (5) ◽  
pp. 2062
Author(s):  
Kane J. Norton ◽  
Firoz Alam ◽  
David J. Lewis
Keyword(s):  
Layer Structure ◽  
Visible Region ◽  
Band Gap Energy ◽  
Bandgap Energy ◽  
Electromagnetic Spectrum ◽  
Optical And Electronic Properties ◽  
Synthesis Properties ◽  
High Absorption Coefficient ◽  
Constituent Elements ◽  
Conversion Efficiencies

Tin(II) sulfide (SnS) is an attractive semiconductor for solar energy conversion in thin film devices due to its bandgap of around 1.3 eV in its orthorhombic polymorph, and a band gap energy of 1.5–1.7 eV for the cubic polymorph—both of which are commensurate with efficient light harvesting, combined with a high absorption coefficient (10−4 cm−1) across the NIR–visible region of the electromagnetic spectrum, leading to theoretical power conversion efficiencies >30%. The high natural abundance and a relative lack of toxicity of its constituent elements means that such devices could potentially be inexpensive, sustainable, and accessible to most nations. SnS exists in its orthorhombic form as a layer structure similar to black phosphorus; therefore, the bandgap energy can be tuned by thinning the material to nanoscale dimensions. These and other properties enable SnS applications in optoelectronic devices (photovoltaics, photodetectors), lithium- and sodium-ion batteries, and sensors among others with a significant potential for a variety of future applications. The synthetic routes, structural, optical and electronic properties as well as their applications (in particular photonic applications and energy storage) of bulk and 2D tin(II) sulfide are reviewed herein.

Relating atomic local structures and Curie temperature of NdFeB permanent magnets: an X-ray absorption spectroscopic study

Rare Metals ◽  
2017 ◽  
Vol 37 (11) ◽  
pp. 983-988 ◽  
Author(s):  
Mu-Nan Yang ◽  
Hang Wang ◽  
Yong-Feng Hu ◽  
Liu-Yi-Mei Yang ◽  
Aimee Maclennan ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Spectroscopic Study ◽  
Permanent Magnets ◽  
X Ray ◽  
Local Structures ◽  
X Ray Absorption

Effect of Different Catalysts and Growth Temperature on the Photoluminescence Properties of Zinc Silicate Nanostructures Grown via VLS Method

2021 ◽  
Author(s):  
Ghfoor Muhammad ◽  
Imran Murtaza ◽  
Rehan Abid ◽  
Naeem Ahmad
Keyword(s):  
Energy Levels ◽  
Visible Region ◽  
Wide Bandgap ◽  
Visible Spectral Range ◽  
Zinc Silicate ◽  
Band Spectrum ◽  
Photoluminescence Properties ◽  
Display Devices ◽  
Crystal Growth Kinetics ◽  
Potential Applications

Abstract Herein, we explore the photoluminescence properties of zinc silicate (Zn2SiO4) nanostructures synthesized by vapor-liquid-solid (VLS) mode of growth using three different catalysts (Sn, Ag and Mn). Different catalysts significantly influence the growth rate which in turn has an impact on the structure and hence the photoluminescence of the prepared zinc silicate nanostructures. Zn2SiO4 has a wide bandgap of about 5.5 eV and in its pure form, it does not emit in visible region due to its inner shell electronic transitions between the 3d5 energy levels. However, the incorporation of different catalysts (Sn, Ag and Mn) at different growth temperatures into the Zn2SiO4 crystal growth kinetics provides wide visible spectral range of photoluminescence (PL) emissions. PL analysis shows broad multi-band spectrum in the visible region and distinct colours (red, yellow, green, blue, cyan and violet) are obtained depending on the crystalline structure of the prepared nanostructures. The allowed transitions due to the effect of different catalysts on zinc silicate lattice offer a huge cross-section of absorption that generates strong photoluminescence. The correlation between the structural and optical properties of the synthesized nanostructures is discussed in detail. The synthesized photoluminescent nanostructures have potential applications in solid-state lighting and display devices.

Fluorescence Extended X-Ray Absorption Fine Structure Study on Local Structures of Rare-Earth-Doped InGaGdN

2016 ◽  
Vol 1133 ◽  
pp. 429-433
Author(s):  
Siti Nooraya Mohd Tawil ◽  
Shuichi Emura ◽  
Daivasigamani Krishnamurthy ◽  
Hajime Asahi
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Nearest Neighbor ◽  
Structure Study ◽  
Edge Structure ◽  
X Ray ◽  
Local Structures ◽  
Absorption Fine ◽  
X Ray Absorption

Local structures around gadolinium atoms in rare-earth (RE)-doped InGaGdN thin films were studied by means of fluorescence extended X-ray absorption fine structure (EXAFS) measured at the Gd LIII-edges. The samples were doped with Gd in-situ during growth by plasma-assisted molecular beam epitaxy (PAMBE). Gd LIII-edge EXAFS signal from the GaGdN, GdN and Gd foil were also measured as reference. The X-ray absorption near edge structure (XANES) spectra around Gd LIII absorption edge of InGaGdN samples observed at room temperature indicated the enhancement of intensities with the increase of Gd composition. Further EXAFS analysis inferred that the Gd atoms in InGaN were surrounded by similar atomic shells as in the case of GaGdN with the evidence indicating majority of Gd atoms substituted into Ga sites of InGaGdN. A slight elongation of bond length for the 2nd nearest-neighbor (Gd–Ga) of sample with higher Gd concentration was also observed.

Study of Band Alignment at CBD-CdS/Cu(In1-xGax)Se2 (x = 0.2 - 1.0) Interfaces by Photoemission and Inverse Photoemission Spectroscopy

2007 ◽  
Vol 1012 ◽  
Author(s):  
Shimpei Teshima ◽  
Hirotake Kashiwabara ◽  
Keimei Masamoto ◽  
Kazuya Kikunaga ◽  
Kazunori Takeshita ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Valence Band Maximum ◽  
Band Gap Energy ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Gap Energy ◽  
Conduction Band Offset ◽  
Inverse Photoemission ◽  
Inverse Photoemission Spectroscopy

AbstractDependence of band alignments at interfaces between CdS by chemical bath deposition and Cu(In1-xGax)Se2 by conventional 3-stage co-evaporation on Ga substitution ratio x from 0.2 to 1.0 has been systematically studied by means of photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). For the specimens of the In-rich CIGS, conduction band minimum (CBM) by CIGS was lower than that of CdS. Conduction band offset of them was positive about +0.3 ~ +0.4 eV. Almost flat conduction band alignment was realized at x = 0.4 ~ 0.5. On the other hand, at the interfaces over the Ga-rich CIGS, CBM of CIGS was higher than that of CdS, and CBO became negative. The present study reveals that the decrease of CBO with a rise of x presents over the wide rage of x, which results in the sign change of CBO around 0.4 ~ 0.45. In the Ga-rich interfaces, the minimum of band gap energy, which corresponded to energy spacing between CBM of CdS and valence band maximum of CIGS, was almost identical against the change of band gap energy of CIGS. Additionally, local accumulation of oxygen related impurities was observed at the Ga-rich samples, which might cause the local rise of band edges in central region of the interface.

scholarly journals Photoluminescence Studies of GaN and AlGaN Layers Under Hydrostatic Pressure

1995 ◽  
Vol 378 ◽  
Author(s):  
C. Wetzel ◽  
W. Walukiewicz ◽  
E. E. Haller ◽  
H. Amano ◽  
I. Akasaki
Keyword(s):  
Hydrostatic Pressure ◽  
Energy Levels ◽  
Wide Bandgap ◽  
High Electron ◽  
Valence Band Edge ◽  
Native Defects ◽  
Free Carriers ◽  
High Electron Concentration ◽  
Localized Defects ◽  
Photoluminescence Studies

AbstractWide bandgap GaN very often shows a high electron concentration. Although several impurities such as O and Si have been identified, the concentration is not high enough to account for the number of free carriers. As a consequence native defects namely the nitrogen vacancies are widely considered to be present at high densities. Several calculations predict different energy levels of this strongly localized defect. We present photoluminescence experiments of wurtzite GaN and AlGaN layers under large hydrostatic pressure to search for localized defects within the questionable energy range of 3 .0 to 3 .8 eV above the valence band edge.

scholarly journals Local structures of isovalent and heterovalent dilute impurities in Si crystal probed by fluorescence x-ray absorption fine structure

1997 ◽  
Vol 82 (10) ◽  
pp. 4810-4815 ◽  
Author(s):  
Shiqiang Wei ◽  
Hiroyuki Oyanagi ◽  
Hitoshi Kawanami ◽  
Kunihiro Sakamoto ◽  
Tsunenori Sakamoto ◽  
...  
Keyword(s):  
Fine Structure ◽  
X Ray ◽  
Local Structures ◽  
Absorption Fine ◽  
X Ray Absorption
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