Selective observation of transverse optical phonons of Au modes to evaluate free charge carrier parameters in β-Ga2O3 substrate and homoepitaxial film

2021 ◽  
Vol 118 (25) ◽  
pp. 252101
Author(s):  
Takeyoshi Onuma ◽  
Kohei Sasaki ◽  
Tomohiro Yamaguchi ◽  
Tohru Honda ◽  
Akito Kuramata ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Free Charge Carrier ◽  
Transverse Optical ◽  
Optical Phonons ◽  
Free Charge ◽  
Homoepitaxial Film

scholarly journals Critical View on Buffer Layer Formation and Monolayer Graphene Properties in High-Temperature Sublimation

2021 ◽  
Vol 11 (4) ◽  
pp. 1891
Author(s):  
Vallery Stanishev ◽  
Nerijus Armakavicius ◽  
Chamseddine Bouhafs ◽  
Camilla Coletti ◽  
Philipp Kühne ◽  
...  
Keyword(s):  
High Temperature ◽  
Charge Carrier ◽  
Buffer Layer ◽  
Free Charge Carrier ◽  
Monolayer Graphene ◽  
Free Charge ◽  
Layer Formation ◽  
Free Hole ◽  
Sublimation Growth ◽  
Insulating Substrates

In this work we have critically reviewed the processes in high-temperature sublimation growth of graphene in Ar atmosphere using closed graphite crucible. Special focus is put on buffer layer formation and free charge carrier properties of monolayer graphene and quasi-freestanding monolayer graphene on 4H–SiC. We show that by introducing Ar at higher temperatures, TAr, one can shift the formation of the buffer layer to higher temperatures for both n-type and semi-insulating substrates. A scenario explaining the observed suppressed formation of buffer layer at higher TAr is proposed and discussed. Increased TAr is also shown to reduce the sp3 hybridization content and defect densities in the buffer layer on n-type conductive substrates. Growth on semi-insulating substrates results in ordered buffer layer with significantly improved structural properties, for which TAr plays only a minor role. The free charge density and mobility parameters of monolayer graphene and quasi-freestanding monolayer graphene with different TAr and different environmental treatment conditions are determined by contactless terahertz optical Hall effect. An efficient annealing of donors on and near the SiC surface is suggested to take place for intrinsic monolayer graphene grown at 2000 ∘C, and which is found to be independent of TAr. Higher TAr leads to higher free charge carrier mobility parameters in both intrinsically n-type and ambient p-type doped monolayer graphene. TAr is also found to have a profound effect on the free hole parameters of quasi-freestanding monolayer graphene. These findings are discussed in view of interface and buffer layer properties in order to construct a comprehensive picture of high-temperature sublimation growth and provide guidance for growth parameters optimization depending on the targeted graphene application.

scholarly journals Cavity-enhanced optical Hall effect in two-dimensional free charge carrier gases detected at terahertz frequencies

2015 ◽  
Vol 40 (12) ◽  
pp. 2688 ◽  
Author(s):  
S. Knight ◽  
S. Schöche ◽  
V. Darakchieva ◽  
P. Kühne ◽  
J.-F. Carlin ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Hall Effect ◽  
Free Charge Carrier ◽  
Two Dimensional ◽  
Free Charge ◽  
Terahertz Frequencies ◽  
Carrier Gases ◽  
Optical Hall Effect

Free charge carrier repartition over the surface of photosensitive materials: Why and how to manage?

2008 ◽  
Vol 78 (5) ◽  
pp. 1070-1080 ◽  
Author(s):  
A. A. Evstratov ◽  
C. Chis ◽  
A. A. Malygin ◽  
J. -M. Taulemesse ◽  
P. Gaudon ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Free Charge Carrier ◽  
Free Charge

SFGP 2007 - Photosensitive Composite Disordered Nanostructures over Acceptor Supports: Selective Free Charge Carrier Generators for Environmental Applications

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Cristain Chis ◽  
Alexis Evstratov
Keyword(s):  
Charge Carrier ◽  
Free Charge Carrier ◽  
Charge Carriers ◽  
Environmental Applications ◽  
Free Charge ◽  
Active Components ◽  
Active Materials ◽  
Photocatalytic Removal ◽  
Volatile Organic

Amorphous and low-ordered photosensitive materials are not usually considered to be promising photocatalytic agents because of extremely short free charge carrier (FCC) lifetimes in their active components deprived of well-defined electronic structures. Using active supports favoring an efficient FCC separation in situ, it is possible to protect free charge carriers from the immediate recombination, so even the disordered photosensitive composites can be provided with important photocatalytic capacities. The examples of some environmental applications of this type of active materials, such as volatile organic compound (VOC) photocatalytic removal and bacteria sterilization, are presented in this paper.

scholarly journals Critical View on Buffer Layer Formation and Monolayer Graphene Properties in High-Temperature Sublimation

2021 ◽  
Author(s):  
Vallery Stanishev ◽  
Nerijus Armakavicius ◽  
Chamseddine Bouhafs ◽  
Camilla Coletti ◽  
Philipp Kuhne ◽  
...  
Keyword(s):  
High Temperature ◽  
Charge Carrier ◽  
Buffer Layer ◽  
Free Charge Carrier ◽  
Monolayer Graphene ◽  
Free Charge ◽  
Layer Formation ◽  
Free Hole ◽  
Sublimation Growth ◽  
Insulating Substrates

In this work we have critically reviewed the processes in high-temperature sublimation growth of graphene in Ar atmosphere using enclosed graphite crucible. Special focus is put on buffer layer formation and free charge carrier properties of monolayer graphene and quasi-freestanding monolayer garphene on 4H-SiC. We show that by introducing Ar at different temperatures, TAr one can shift to higher temperatures the formation of the buffer layer for both n-type and semi-insulating substrates. A scenario explaining the observed suppresed formation of buffer layer at higher TAr is proposed and discussed. Increased TAr is also shown to reduce the sp3 hybridization content and defect densities in the buffer layer on n-type conductive substrates. Growth on semi-insulating substrates results in ordered buffer layer with significantly improved structural properties, for which TAr plays only a minor role. The free charge density and mobility parameters of monolayer graphene and quasi-freestanding monolayer graphene with different TAr and different environmental treatment conditions are determined by contactless terahertz optical Hall effect. An efficient annealing of donors on and near the SiC surface takes place in intrinsic monolayer graphene grown at 2000∘C, and which is found to be independent of TAr. Higher TAr leads to higher free charge carrier mobility parameters in both intrinsically n-type and ambient p-type doped monolayer graphene. TAr is also found to have a profound effect on the free hole parameters of quasi-freestanding monolayer graphene. These findings are discussed in view of interface and buffer layer properties in order to construct a comprehensive picture of high-temperature sublimation growth and provide guidance for growth parameters optimization depending on the targeted graphene application.

The Locus of Free Charge-Carrier Generation in Solution-Cast Zn1–xMgxO/Poly(3-hexylthiophene) Bilayers for Photovoltaic Applications

2007 ◽  
Vol 17 (18) ◽  
pp. 3849-3857 ◽  
Author(s):  
J. Piris ◽  
N. Kopidakis ◽  
D. C. Olson ◽  
S. E. Shaheen ◽  
D. S. Ginley ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Free Charge Carrier ◽  
Free Charge ◽  
Carrier Generation ◽  
Photovoltaic Applications ◽  
Solution Cast

Investigation of free charge carrier effects in silicon membranes

2015 ◽  
Author(s):  
W. I. Ndebeka ◽  
P. H. Neethling ◽  
C. M. Steenkamp ◽  
H. Stafast ◽  
E. G. Rohwer
Keyword(s):  
Charge Carrier ◽  
Free Charge Carrier ◽  
Free Charge ◽  
Silicon Membranes
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