Electrolyte Electroreflectance of Boron Phosphide (BP)

1996 ◽  
Vol 451 ◽  
Author(s):  
E. Schroten ◽  
A. Goossens ◽  
J. Schoonman
Keyword(s):  
Thin Films ◽  
Energy Level ◽  
Critical Point ◽  
Conduction Band ◽  
Interference Effects ◽  
First Report ◽  
Direct Bandgap ◽  
Incident Photon ◽  
Boron Phosphide ◽  
Pronounced Peak

ABSTRACTAn electrolyte electroreflectance study has been performed on boron phosphide thin films epitaxially grown on silicon (100) substrates. To our knowledge, this paper is the first report on the electrolyte electroreflectance spectrum of BP. All our boron phosphide of 1.5 μm thick films show a pronounced peak at the energy 4.25 eV, indicating a critical point in the valence or conduction band of the semiconductor. Photoreflectance measurements confirm these results. The 4.25 eV energy level is much lower than previously reported direct bandgap values of BP. The electrolyte electroreflectance spectrum of much thinner layers shows, besides the 4.25 eV peak, some other features at still lower incident photon energies caused by interference effects.

Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

1983 ◽  
Vol 41 ◽  
pp. 606-607
Author(s):  
Klaus-Ruediger Peters ◽  
Samuel A. Green
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Critical Point ◽  
Metal Films ◽  
High Magnification ◽  
Osmium Impregnation ◽  
Instrumental Resolution ◽  
20 Nm ◽  
Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

scholarly journals Energy Level Engineering of Charge Selective Contact and Halide Perovskite by Modulating Band Offset: Mechanistic Insights

2020 ◽  
Author(s):  
Yassine Raoui ◽  
Hamid Ez-Zahraouy ◽  
Samrana Kazim ◽  
Shahzada Ahmad
Keyword(s):  
Solar Cells ◽  
Energy Level ◽  
Conduction Band ◽  
Perovskite Solar Cells ◽  
Hole Transport ◽  
Conduction Band Minimum ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Band Offset ◽  
Interfacial Recombination

<p>Mixed cation and anion based perovskites solar cells (FAPbI<sub>3</sub>)<sub>0.85</sub>(MAPbBr<sub>3</sub>)<sub>0.15</sub> gave enhanced stability under outdoor conditions, however, it yielded limited power conversion efficiency when SnO<sub>2</sub> and Spiro-OMeTAD were employed as electron and hole transport layer (ETL/HTL). The inevitable interfacial recombination of charge carriers at ETL/perovskite and perovskite/HTL interface diminished the efficiency in planar (n-i-p) perovskite solar cells. Employing computational approach for uni-dimensional device simulator, the effect of band offset on charge recombination at both interfaces were investigated. We noted that it acquired cliff structure when the conduction band minimum of the ETL is lower than that of the perovskite, and thus maximizes interfacial recombination. However, if the conduction band minimum of ETL is higher than perovskite, i.e. spike structure is formed, which improve the performance of solar cell up to an optimum value of conduction band offset allowing to reach performance of 25.21%, with an open circuit voltage (<i>V</i><sub>oc</sub>) of 1231 mV, a current density <i>J</i><sub>sc</sub> of 24.57 mA/cm<sup>2</sup> and a fill factor of 83.28%. Additionally, we found that beyond the optimum offset value, large spike structure could decrease the performance. With an optimized, energy level of Spiro-OMeTAD and the thickness of mixed-perovskite layer performance of 26.56 % can be attained. Our results demonstrate a detailed understanding about the energy level tuning between the charge selective layers and perovskite and furthermore how the improvement in PV performance can be achieved by adjusting the energy level offset.</p>

Doping and Annealing Effects on the Optical Bandgap of the Nickel Doped Copper Oxide Thin Films

2021 ◽  
Vol 16 (2) ◽  
pp. 243-248
Author(s):  
Fatmah S. Bahabri ◽  
Alaa Y. Mahmoud ◽  
Wafa A. Alghameeti
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Doping Concentration ◽  
Cupric Oxide ◽  
Optical Bandgap ◽  
Visible Range ◽  
Bandgap Energy ◽  
Direct Bandgap ◽  
Annealing Temperatures ◽  
Annealing Effects

In this work, we study the optical properties of the Nickel doped cupric oxide Ni-CuO thin films with Ni various doping concentrations (0, 20, 30, 50, 70, and 80%), at two different annealing temperatures; 200 and 400 °C. The absorbance and optical bandgap for the films are calculated and compared. We find that all films exhibit clear peaks in the visible range, with the increase in the absorptivity via increasing both annealing and Ni concentration. We also find that the annealing affects the shape of the absorbance peaks to be narrowed and blue shifted. Investigation on the direct bandgap energy shows that all films exhibit large direct gap; ranging from 3.87 to 4.01 eV. For non-annealed films, direct bandgap increases with increasing the Ni concentration, while for the annealed samples, the direct bandgap generally decreases by annealing, and with increasing the doping concentration. For the indirect bandgap analysis, the calculated values of the bandgap are ranging from 0.62 to 1.96 eV. We find that for non-annealed films, the indirect bandgap increases with increasing the doping concentration, while after annealing, the bandgap decreases with increasing the doping concentration for the annealing at 200 and 400 °C, with more decreasing in the gap at 400 °C.

Growth of Rhombohedral B12P2 Thin Films on 6H-SiC(0001) By Chemical Vapor Deposition

2003 ◽  
Vol 799 ◽  
Author(s):  
Peng Lu ◽  
J. H. Edgar ◽  
J. Pomeroy ◽  
M. Kuball ◽  
H. M. Meyer ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Flow Rate ◽  
Growth Rates ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Flow Rate Ratio ◽  
Good Surface ◽  
Boron Phosphide ◽  
Moderate Growth

ABSTRACTThe parameters necessary to deposit oriented rhombohedral boron phosphide (B12P2) thin films on on-axis Si-face 6H-SiC(0001) substrates by chemical vapor deposition are reported. Ultra high purity BBr3 and PBr3 were used as reactants, with hydrogen as the carrier gas. The BBr3 to PBr3 flow rate ratio was adjusted to obtain good surface morphology of the B12P2 films. BBr3 to PBr3 ratios in the range of 1 to 1.5 produced smooth surfaces and moderate growth rates of 10μm/hr. Higher growth rates were obtained by increasing the BBr3 flow rate, but the surfaces became very rough. The c-axis of the B12P2 film was aligned with the c -axis of the substrate at temperatures between 1650°C-1700°C. The surface morphologies were investigated by SEM and the crystalline properties of the films were characterized by XRD and Raman spectroscopy.

Optical analysis of doped ZnO thin films using nonparabolic conduction-band parameters

2012 ◽  
Vol 111 (12) ◽  
pp. 123507 ◽  
Author(s):  
J. S. Kim ◽  
J.-h. Jeong ◽  
J. K. Park ◽  
Y. J. Baik ◽  
I. H. Kim ◽  
...  
Keyword(s):  
Thin Films ◽  
Conduction Band ◽  
Zno Thin Films ◽  
Optical Analysis ◽  
Doped Zno

Accuracy of the Energy Distribution of the Interface States at the SiO2/SiC Interface by Conductance Method

2016 ◽  
Vol 858 ◽  
pp. 437-440
Author(s):  
Munetaka Noguchi ◽  
Toshiaki Iwamatsu ◽  
Hiroyuki Amishiro ◽  
Hiroshi Watanabe ◽  
Shuhei Nakata ◽  
...  
Keyword(s):  
Energy Level ◽  
Energy Distribution ◽  
Conduction Band ◽  
Interface States ◽  
Oxide Semiconductor ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Electrical Characteristics ◽  
Conductance Method ◽  
Effect Transistor

The electrical characteristics of the SiC metal-oxide-semiconductor field effect transistor (MOSFET) have been limited by large amount of states at the SiO2/SiC interface. In this study, the accuracy of the energy level of the interface states extracted by hypothetical high frequency extreme, which is conventionally used, is experimentally examined. Conductance measurements at low temperature between 65 K and 100 K reveal that the extracted energy distribution of the interface states at nitrided SiO2/SiC interface close to the conduction band edge depends on the measurement temperature. It is demonstrated that conductance method at 65K enables us more accurate evaluation of the interface states at the SiO2/SiC interface and found that the interface states density (Dit) of nitride SiO2/SiC interface is over 1013 cm-2eV-1 at energy level of 0.1 eV below the conduction band edge.

Superior supercapacitive performance of grass-like CuO thin films deposited by liquid phase deposition

2020 ◽  
Vol 44 (17) ◽  
pp. 6778-6790 ◽  
Author(s):  
Shreelekha N. Khatavkar ◽  
Shrikrishna D. Sartale
Keyword(s):  
Thin Films ◽  
Stainless Steel ◽  
Liquid Phase ◽  
Liquid Phase Deposition ◽  
Supercapacitive Performance ◽  
First Report

First report on deposition and supercapacitive performance of grass-like CuO thin films by liquid phase deposition on flat and mesh stainless steel (SS). The maximum specific capacitances on flat and mesh SS are 552 and 849 F g−1.

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