Luminescence and EPR Study of Lithium-Diffused ZnO Crystals

2002 ◽  
Vol 744 ◽  
Author(s):  
N. Y. Garces ◽  
Lijun Wang ◽  
M. M. Chirila ◽  
L. E. Halliburton ◽  
N. C. Giles
Keyword(s):  
Room Temperature ◽  
Deep Level ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Paramagnetic Resonance ◽  
Lithium Diffusion ◽  
Before And After ◽  
Electron Paramagnetic ◽  
Transport Method

ABSTRACTZinc oxide (ZnO) crystals grown by the seeded chemical vapor transport method have been studied using photoluminescence (PL), thermoluminescence (TL), and electron paramagnetic resonance (EPR) techniques. Lithium acceptors were diffused into the crystals during anneals in LiF powder at temperatures in the 750 to 850°C range. After a lithium diffusion, EPR was used to monitor neutral lithium acceptors and neutral shallow donors, as well as Ni3+, Fe3+, and Cu2+ impurities unintentionally present. Excitonic and deep-level PL emissions were also monitored before and after these diffusions. Two broad overlapping TL emission bands were observed at 117 and 145 K when a Li-diffused crystal was illuminated at 77 K with 325-nm light and then rapidly warmed to room temperature. The two TL bands have the same spectral dependence (the peak in wavelength is 540 nm when the intensity of the light reaches a maximum). These “glow” peaks occur when electrons are thermally released from Ni2+ and Fe2+ ions and recombine with holes at neutral lithium acceptors.

Characterization of Semi-insulating SiC

2006 ◽  
Vol 911 ◽  
Author(s):  
Nguyen Tien Son ◽  
Patrick Carlsson ◽  
Björn Magnusson ◽  
Erik Janzén
Keyword(s):  
Vapor Deposition ◽  
Thermal Activation ◽  
Deep Level ◽  
Chemical Vapor ◽  
Activation Energies ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

AbstractElectron paramagnetic resonance was used to study defects in high-purity semi-insulating (HPSI) substrates grown by high-temperature chemical vapor deposition and physical vapor transport. Deep level defects associated to different thermal activation energies of the resistivity ranging from ~0.6 eV to ~1.6 eV in HPSI substrates are identified and their roles in carrier compensation processes are discussed. Based on the results obtained in HPSI materials, we discuss the carrier compensation processes in vanadium-doped SI SiC substrates and different activation energies in the material.

In situ formation of highly exposed NiPS3 nanosheets on nickel foam as an efficient 3D electrocatalyst for overall water splitting

2021 ◽  
Author(s):  
Liang Fang ◽  
Yanping Xie ◽  
Peiyin Guo ◽  
Jingpei Zhu ◽  
Shuhui Xiao ◽  
...  
Keyword(s):  
Water Splitting ◽  
Nickel Foam ◽  
Chemical Vapor ◽  
Bifunctional Catalyst ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Overall Water Splitting ◽  
One Step ◽  
Transport Method

Vertical NiPS3 nanosheets in situ grown on conducting nickel foam were fabricated by a facile one-step chemical vapor transport method and used as an efficient bifunctional catalyst for overall water splitting.

One-step synthesis of a hierarchical self-supported WS2 film for efficient electrocatalytic hydrogen evolution

2019 ◽  
Vol 7 (39) ◽  
pp. 22405-22411 ◽  
Author(s):  
Min Wang ◽  
Li Zhang ◽  
Meirong Huang ◽  
Qifan Zhang ◽  
Xuanliang Zhao ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hierarchical Structure ◽  
Hydrogen Evolution Reaction ◽  
Chemical Vapor ◽  
Tungsten Disulfide ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
One Step ◽  
Transport Method ◽  
Vapor Transport Method

A tungsten disulfide film with a hierarchical structure is synthesized by surface-assisted chemical vapor transport method and applied as a self-supported electrode for the hydrogen evolution reaction, showing superior electrocatalytic performance.

Structural and physical properties of FeSe crystals fabricated by the chemical vapor transport method

2010 ◽  
Vol 470 ◽  
pp. S313-S314 ◽  
Author(s):  
Y. Hara ◽  
K. Takase ◽  
A. Yamasaki ◽  
H. Sato ◽  
N. Miyakawa ◽  
...  
Keyword(s):  
Physical Properties ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Transport Method ◽  
Vapor Transport Method

scholarly journals Epr Spectrum Angular Dependences In Liyf4 Crystal / Epr Spektru Leņķiskās Atkarības Liyf4 Kristālā

2012 ◽  
Vol 49 (6-I) ◽  
pp. 49-54
Author(s):  
A. Antuzevics ◽  
A. Fedotovs ◽  
U. Rogulis
Keyword(s):  
Room Temperature ◽  
Temperature Analysis ◽  
Epr Spectrum ◽  
Spectral Parameters ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Crystal Growth Process ◽  
Before And After ◽  
Impurity Ion ◽  
Electron Paramagnetic

Abstract Electron paramagnetic resonance (EPR) measurements have been made for two perpendicular planes in a LiYF4 crystal before and after x-ray irradiation at room temperature. Analysis of the EPR spectrum angular dependence shows the presence of two defects - an impurity ion, which was embedded during the crystal growth process, and an x-ray induced defect with the g-factor of approx. 2.0. Spectral parameters and possible defect models are discussed.

Experimental Evidence for Nitrogen as a Deep Acceptor in ZnO

2011 ◽  
Vol 1394 ◽  
Author(s):  
M.C. Tarun ◽  
M. Zafar Iqbal ◽  
M.D. McCluskey ◽  
J. Huso ◽  
L. Bergman
Keyword(s):  
Nitrogen Doping ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Excitation Threshold ◽  
Bulk Single Crystal ◽  
Deep Acceptor ◽  
The Past ◽  
Configuration Coordinate

ABSTRACTWhile zinc oxide is a promising material for blue and UV solid-state lighting devices, the lack of p-type doping has prevented ZnO from becoming a dominant material for optoelectronic applications. Over the past decade, numerous reports have claimed that nitrogen is a viable p-type dopant in ZnO. However, recent calculations by Lyons, Janotti, and Van de Walle [Appl. Phys. Lett. 95, 252105 (2009)] suggest that nitrogen is a deep acceptor. In our work, we performed photoluminescence (PL) measurements on bulk, single crystal ZnO grown by chemical vapor transport. Nitrogen doping was achieved by growing in ammonia. In prior work at room temperature, we observed a broad PL band at ∼1.7 eV, with an excitation threshold of ∼2.2 eV, consistent with the calculated configuration-coordinate diagram. In the present work, at liquid-helium temperatures, the PL emission increases in intensity and red-shifts by ∼0.2 eV. A peak is observed at 3.267 eV, which we tentatively attribute to an exciton bound to a nitrogen acceptor. Our experimental results indicate that nitrogen is indeed a deep acceptor and cannot be used to produce p-type ZnO.

scholarly journals High Optical Response of Niobium-Doped WSe2-Layered Crystals

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1161 ◽  
Author(s):  
Hung-Pin Hsu ◽  
Der-Yuh Lin ◽  
Jhin-Jhong Jheng ◽  
Pin-Cheng Lin ◽  
Tsung-Shine Ko
Keyword(s):  
Chemical Vapor ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Near Band Edge ◽  
Frequency Dependent ◽  
Time Resolved ◽  
Niobium Doped ◽  
Layered Crystals ◽  
Transport Method ◽  
Vapor Transport Method

The optical properties of WSe2-layered crystals doped with 0.5% niobium (Nb) grown by the chemical vapor transport method were characterized by piezoreflectance (PzR), photoconductivity (PC) spectroscopy, frequency-dependent photocurrent, and time-resolved photoresponse. With the incorporation of 0.5% Nb, the WSe2 crystal showed slight blue shifts in the near band edge excitonic transitions and exhibited strongly enhanced photoresponsivity. Frequency-dependent photocurrent and time-resolved photoresponse were measured to explore the kinetic decay processes of carriers. Our results show the potential application of layered crystals for photodetection devices based on Nb-doped WSe2-layered crystals.

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