Surface and dynamical properties of GeI2

2D Materials ◽  
2021 ◽  
Author(s):  
Archit Dhingra ◽  
Alexey Lipatov ◽  
Haidong Lu ◽  
Katerina Chagoya ◽  
Joseph Dalton ◽  
...  
Keyword(s):  
Band Gap ◽  
Debye Temperature ◽  
Wide Band ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Bulk Temperature ◽  
Level Shift ◽  
Temperature Dependent ◽  
X Ray ◽  
Optical Absorbance

Abstract GeI2 is an interesting two-dimensional (2D) wide-band gap semiconductor because of diminished edge scattering due to an absence of dangling bonds. Angle-resolved x-ray photoemission spectroscopy (ARXPS) indicates a germanium rich surface, and a surface to bulk core-level shift of 1.8 eV in binding energy, between the surface and bulk components of the Ge 2p3/2 core-level, making clear that the surface is different from the bulk. Temperature dependent studies indicate an effective Debye temperature (θD ) of 186 ± 18 K for the germanium x-ray photoemission spectroscopy (XPS) feature associated with the surface. These measurements also suggest an unusually high effective Debye temperature for iodine (587 ± 31 K), implying that iodine is present in the bulk of the material, and not the surface. From optical absorbance, GeI2 is seen to have an indirect (direct) optical band gap of 2.60 (2.8) ± 0.02 (0.1) eV, consistent with the expectations. Temperature dependent magnetometry indicates that GeI2 is moment paramagnetic at low temperatures (close to 4 K) and shows a diminishing saturation moment at high temperatures (close to 300 K and above).

scholarly journals The Debye Temperature for Hydrothermally Grown ThO2 Single Crystals

2013 ◽  
Vol 1576 ◽  
Author(s):  
Tony D. Kelly ◽  
James C. Petrosky ◽  
John W. McClory ◽  
Timothy Zens ◽  
David Turner ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Single Crystals ◽  
Debye Temperature ◽  
Oxidation State ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Temperature Dependent ◽  
X Ray ◽  
Temperature Range

ABSTRACTThe electronic properties of ThO2 single crystals were studied using x-ray photoemission spectroscopy (XPS). The XPS results show that the Th 4f core level is in an oxidation state that is consistent with that expected for Th in ThO2. The effective Debye temperature is estimated from the temperature dependent photoemission intensities of the Th 4f core level over the temperature range of 290 to 360 K. A Debye temperature of 468±32 K has been determined.

scholarly journals Study of Band Gap of Silver Nanoparticles—Titanium Dioxide Nanocomposites

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
P. Barone ◽  
F. Stranges ◽  
M. Barberio ◽  
D. Renzelli ◽  
A. Bonanno ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Band Gap ◽  
Chemical Properties ◽  
Photoelectrochemical Cells ◽  
Visible Range ◽  
X Ray ◽  
Optical Absorbance ◽  
Laser Ablation Process ◽  
Uv Visible ◽  
And Chemical Properties

The optical and chemical properties of Ag/TiO2nanocomposites were investigated to explore the possibilities of incorporating these new materials in Gratzel photoelectrochemical cells. The nanocomposites were obtained doping TiO2, in both allotropic species anatase and rutile, with silver nanoparticles (grown by laser ablation process). X-ray photoelectron data indicate the absence of Ag-Ti chemical bonds, while measurements of photoluminescence and optical absorbance in UV-visible range show a quench in photoluminescence emission of about 50% and an increase in visible absorbance of about 20%. Measurements of optical band gap, obtained by Tauc’s equation, indicate a variation of about 1.6 eV.

Chemical Structure of MEH-PPV/LiF/Al Interface

2002 ◽  
Vol 734 ◽  
Author(s):  
X. D. Feng ◽  
D. Grozea ◽  
Z. H. Lu
Keyword(s):  
Oxygen Concentration ◽  
Chemical Structure ◽  
Electron Injection ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
X Ray ◽  
Electron Injection Layer

ABSTRACTWe studied the poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV)/LiF/Al interface by angle-dependent X-ray photoemission spectroscopy (XPS). The changes in the C1s, O 1s, Al 2p core level spectra, and the evolution of O to C and Li to F atomic ratios at different photoelectron take-off angles were carefully analyzed. A reduced oxygen concentration with a LiF layer at the interface suggests that LiF can help reduce the oxidation of Al. The interface was found rich in Li+ ions, some of which might be attached to MEH-PPV to form “N type” doping. The electron injection layer consists of Li+doped MEH-PPV, LiF, Al oxides, and metallic Al.

Band alignment at CdS/wide-band-gap Cu(In,Ga)Se2 hetero-junction by using PES/IPES

2005 ◽  
Vol 865 ◽  
Author(s):  
S.H. Kong ◽  
H. kashiwabara ◽  
K. Ohki ◽  
K. Itoh ◽  
T. Okuda ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Ion Beam ◽  
Wide Band ◽  
Valence Band Maximum ◽  
Conduction Band Minimum ◽  
Band Alignment ◽  
Interface Region ◽  
Photoemission Spectroscopy ◽  
Wide Gap

AbstractDirect characterization of band alignment at chemical bath deposition (CBD)-CdS/Cu0.93 (In1-xGax)Se2 has been carried out by photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). Ar ion beam etching at the condition of the low ion kinetic energy of 350 eV yields a removal of surface contamination as well as successful measurement of the intrinsic properties of each layer and the interfaces. Especially interior regions of the wide gap CIGS layers with a band gap of 1.4 ∼ 1.6 eV were successfully exposed. IPES spectra revealed that the conduction band offset (CBO) at the interface region of the wide gap CIGS with x = 0.60 and 0.75 was negative, where the conduction band minimum of CdS was lower than that of CIGS. It was also observed that the energy spacing between conduction band minimum (CBM) of CdS layer and valence band maximum (VBM) of Cu0.93(In0.25Ga0.75)Se2 layer at interface region was no wider than that of the interface over the Cu0.93(In0.60Ga0.40)Se2 layer.

Sign in / Sign up

Export Citation Format

Share Document