Charge transport variation from Bloch–Grüneisen to Mott variable range hopping and transport change due to hydrogenation in Palladium thin films

AbstractWe report a systematic investigation of the differences in charge transport mechanism in ultra-thin nano-island like films of palladium with thickness varying between 5 nm and 3 nm. The thicker films were found to be metallic in a large temperature range with a dominant Bloch–Grüneisen mechanism of charge transport arising due to electron-acoustic phonon scattering. These films were also found to exhibit an additional electron–magnon scattering. At temperatures below 20 K, the two films displayed a metal-insulator transition which was explained using Al’tshuler’s model of increased scattering in disordered conductors. The thinner films were insulating and were found to exhibit Mott’s variable range hopping mechanism of charge transport. The thinnest film showed a linear decrease of resistance with an increase in temperature in the entire temperature range. The island-like thin films were found to display very different response to hydrogenation at room temperature where the metallic films were found to display a decrease of resistance while the insulating films were found to have an increase of resistance. The decrease of resistance was ascribed to a hydrogen induced lattice expansion in the thin films that were at the percolation threshold while the resistance increase to an increase in work function of the films due to an increased adsorption of the hydrogen atoms at the surface sites of palladium.

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Charge Transport in Thin Films of Polyaniline: Variable-Range Hopping in a Parabolic Quasi-Gap

physica status solidi (b) ◽

10.1002/(sici)1521-3951(199801)205:1<315::aid-pssb315>3.0.co;2-7 ◽

1998 ◽

Vol 205 (1) ◽

pp. 315-318 ◽

Cited By ~ 5

Author(s):

P. Granholm ◽

J. Paloheimo ◽

H. Stubb

Keyword(s):

Thin Films ◽

Charge Transport ◽

Variable Range Hopping ◽

Variable Range

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Mott variable range hopping transport in thermal evaporated vanadyl 2, 3 naphthalocyanine thin films

Materials Chemistry and Physics ◽

10.1016/j.matchemphys.2021.125029 ◽

2021 ◽

pp. 125029

Author(s):

I. Dhanya ◽

Malathy Krishnan ◽

Reny Renji ◽

M.K. Anu ◽

Rachel G. Varghese ◽

...

Keyword(s):

Thin Films ◽

Variable Range Hopping ◽

Hopping Transport ◽

Variable Range

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Processing and Characterization of Amorphous Copper Oxide Thin Films Prepared by Reactive Magnetron Sputtering

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.775.238 ◽

2018 ◽

Vol 775 ◽

pp. 238-245 ◽

Cited By ~ 1

Author(s):

Thitinai Gaewdang ◽

Ngamnit Wongcharoen

Keyword(s):

Thin Films ◽

Low Temperature ◽

Magnetron Sputtering ◽

Copper Oxide ◽

Flow Rate ◽

Localized States ◽

Positive Sign ◽

Variable Range Hopping ◽

Variable Range ◽

Deposited Films

In this paper, copper oxide (CuOx) thin films with amorphous phase were prepared on glass substrates by reactive dc magnetron sputtering. The influence of the flow rate of O2 on the structural, optical and electrical properties of the as-deposited films was systematically studied. XRD revealed that the as-deposited films remained amorphous in the whole range of adjusted oxygen flow rate. Surface morphology and nanoparticle size of the films were observed by AFM. Electrical resistivity and Hall effect measurements were performed on the films with van der Pauw configuration. The positive sign of the Hall coefficient confirmed the p-type conductivity in all studied films. From temperature-dependent electrical conductivity of the films prepared at R(O2) of 1.5 sccm, it was show that three types of behavior can be expected, nearest-neighbor hopping at high temperature range (200-300 K), the Mott variable range hopping at low temperature (110-190 K) and Efros-Shklovskii variable range hopping at very low temperature (65-100 K). Some important parameters corresponding to Mott-VRH and ES-VRH like density of localized states near the Fermi level, localization length, degree of disorder, hopping distance and hopping energy were determined. These parameters would be helpful for optimizing the performance of photovoltaic applications.

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Variable Range Hopping in Single-Wall Carbon Nanotube Thin Films: A Processing–Structure–Property Relationship Study

Langmuir ◽

10.1021/la401264r ◽

2013 ◽

Vol 29 (27) ◽

pp. 8694-8702 ◽

Cited By ~ 30

Author(s):

Sida Luo ◽

Tao Liu ◽

Shermane M. Benjamin ◽

James S. Brooks

Keyword(s):

Thin Films ◽

Carbon Nanotube ◽

Variable Range Hopping ◽

Structure Property ◽

Single Wall Carbon Nanotube ◽

Single Wall Carbon ◽

Variable Range ◽

Property Relationship ◽

Structure Property Relationship ◽

Relationship Study

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Variable range hopping conduction in ZnO nanocrystal thin films

Nanotechnology ◽

10.1088/1361-6528/aad6ce ◽

2018 ◽

Vol 29 (41) ◽

pp. 415202 ◽

Cited By ~ 2

Author(s):

Brian T Benton ◽

Benjamin L Greenberg ◽

Eray Aydil ◽

Uwe R Kortshagen ◽

S A Campbell

Keyword(s):

Thin Films ◽

Hopping Conduction ◽

Variable Range Hopping ◽

Variable Range ◽

Variable Range Hopping Conduction ◽

Zno Nanocrystal

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Space charge limited current, variable range hopping and mobility gap in thermally evaporated amorphous InSe thin films

Journal of Materials Science Materials in Electronics ◽

10.1023/b:jmse.0000045300.00451.51 ◽

2004 ◽

Vol 15 (12) ◽

pp. 787-792 ◽

Cited By ~ 11

Author(s):

C. Viswanathan ◽

S. Gopal ◽

M. Thamilselvan ◽

K. PremNazeer ◽

D. Mangalaraj ◽

...

Keyword(s):

Thin Films ◽

Space Charge ◽

Space Charge Limited Current ◽

Variable Range Hopping ◽

Variable Range ◽

Limited Current ◽

Mobility Gap ◽

Space Charge Limited

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Electrical Transport Properties ofNi95Ti5Catalyzed Multi wall Carbon Nanotubes Film

Journal of Nanomaterials ◽

10.1155/2009/429867 ◽

2009 ◽

Vol 2009 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Zishan Husain Khan ◽

Numan Salah ◽

Sami Habib

Keyword(s):

Carbon Nanotubes ◽

Temperature Region ◽

Electrical Transport ◽

Conduction Mechanism ◽

Variable Range Hopping ◽

Electrical Transport Properties ◽

Multi Wall Carbon Nanotubes ◽

Variable Range ◽

Temperature Range ◽

Dimensional Variable

Carbon nanotubes (CNTs) can be understood as one or more graphite sheets rolled up into a seamless cylinder. CNTs have gained much attention and scientific interest due to their unique properties and potential applications since their discovery in 1991. In the present work, we have deposited Ni95Ti5 film using thermal deposition method. Finally, theNi95Ti5catalyzed multi wall carbon nanotubes (MWNTs) are grown on silicon substrate using low pressure chemical vapor deposition (LPCVD) method and the electrical transport properties of this MWNTs film are studied over a temperature range (284–4K) to explain the conduction mechanism. We have suggested two types of conduction mechanism for the entire temperature range. For the temperature region (284–220K), the conduction is due to thermally activated process, whereas the conduction takes place via variable range hopping (VRH) for the temperature range of (220–4K). The VRH mechanism changes from three dimensions to two dimensions as we move down to the temperature below 50K. Therefore, the data for the temperature region (220–50K) is plotted for three dimensional variable range hopping (3D VRH) model and the two dimensional variable range hopping (2D VRH) for lower temperature range of (50–4K). These VRH models give a good fit to the experimental data. Using these models, we have calculated various interesting electrical parameters such as activation energy, density of states, hopping distance and hopping energy.

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