Electrical Transport in Mesoporous Silicon Layers

ABSTRACTIn order to clarify the role of the enlarged surface area of porous silicon on the electrical conductivity, we have studied the transport in mesoporous silicon layers, for which quantum confinement effects are negligible. We prepare free standing mesoporous films, from highly doped p-type Si wafers. The dark conductivity of the mesoporous layers is activated with an energy of 0.5 eV. Thermopower measurements show negative sign indicating electron conduction. The exposure of these layers to methanol vapor results in an increased conductivity and change of the thermopower magnitude. Photoconductivity measurements and the Steady-State Photocarrier Grating technique (SSPG) are used to evaluate the density of the surface states and the dynamics of the photo-excited carriers. All these results indicate that a large density of surface states exist, which results in a depletion of the free holes.

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Microscopic Understanding of the Carrier Transport Process in Ge Nanocrystals Films

Journal of Nanomaterials ◽

10.1155/2018/2685210 ◽

2018 ◽

Vol 2018 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Dan Shan ◽

Hongyu Wang ◽

Mingjun Tang ◽

Jun Xu

Keyword(s):

Carrier Transport ◽

Surface States ◽

Chemical Vapor ◽

Dark Conductivity ◽

Linear Relationships ◽

P Type ◽

Hydrogenated Amorphous ◽

Hydrogenated Amorphous Germanium ◽

Deposited Film ◽

Ge Nanocrystals

Hydrogenated amorphous germanium (a-Ge:H) films were prepared by a plasma enhanced chemical vapor deposition (PECVD) technique. Ge nanocrystals (Ge NCs) films were obtained by thermal annealing of the as-deposited samples at various temperatures. P-type behavior in Ge NCs films without any external doping was attributed to the holes accumulation caused by acceptor-like surface states. It can be found that the dark conductivity and Hall mobility reached as high as 25.6 S/cm and 182 cm2/V·s in the Ge NCs film annealed at 500°C, which were increased by over four and three orders of magnitude higher than that of the as-deposited film (1.3 × 10-3 S/cm and 0.14 cm2/V·s, resp.). Carrier transport mechanisms of Ge NCs films association with the microstructural characteristics were investigated. Three kinds of temperature-dependent conductivity behaviors, which exhibit the linear relationships of ln⁡σ versus T-1/4, T-1/2, and T-1, respectively, were observed in the temperature regions from 10 K to 500 K, showing different microscopic mechanisms governing carrier transport in Ge NCs film.

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Electrical transport in InAs/GaSb superlattice: role of surface states and interface roughness

Semiconductor Science and Technology ◽

10.1088/0268-1242/27/10/105025 ◽

2012 ◽

Vol 27 (10) ◽

pp. 105025 ◽

Cited By ~ 3

Author(s):

T V Chandrasekhar Rao ◽

Selvakumar V Nair ◽

Harry E Ruda ◽

J Antoszewski ◽

J B Rodriguez ◽

...

Keyword(s):

Electrical Transport ◽

Surface States ◽

Interface Roughness

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Role of surface states in contributing to p-type carrier concentration of vacuum deposited thin germanium films

Solid-State Electronics ◽

10.1016/0038-1101(65)90160-7 ◽

1965 ◽

Vol 8 (12) ◽

pp. 957-960 ◽

Cited By ~ 8

Author(s):

R.R. Humphris ◽

A. Catlin

Keyword(s):

Carrier Concentration ◽

Surface States ◽

Germanium Films ◽

P Type

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Fabrication, Characterization and Electronic Properties of Bismuth Nanowire Systems

MRS Proceedings ◽

10.1557/proc-545-351 ◽

1998 ◽

Vol 545 ◽

Cited By ~ 5

Author(s):

Zhibo B. Zhang ◽

M. S. Dresselhaus ◽

Jackie Y. Ying

Keyword(s):

Aspect Ratio ◽

Electrical Transport ◽

Nanowire Array ◽

Anodic Alumina ◽

Electrical Transport Properties ◽

Free Standing ◽

Electron Effective Mass ◽

Quantum Confinement Effects ◽

Bi Nanowire ◽

Low Dimensional

AbstractWe have fabricated ultra-fine Bi nanowire (10–120 nm) arrays with packing densities as high as 7.1 × 1010/cm2 by pressure injecting its liquid melt into the evacuated nano-channels of an anodic alumina template. Using this fabrication technique, we have also prepared Te-doped n-type Bi nanowires. Free-standing Bi nanowires with an aspect ratio (length/diameter) higher than 500 are obtained by etching away the anodic alumina matrix without attacking the Bi. The resulting Bi nanowires are shown to be single crystals (with the same crystal structure as bulk Bi) and all the wires of a nanowire array are similarly oriented along the wire axis. The small electron effective mass of Bi, the high anisotropy of its Fermi surface, and the large aspect ratio of the Bi nanowires make this a very promising material for low-dimensional thermoelectric applications and an excellent system for studying quantum confinement effects in a quasi-one-dimensional (1D) electron gas. A theoretical model based on the basic band structure of bulk Bi, suitably modified for the 1D situation, is constructed to explore the electrical transport properties of Bi nanowires, which are expected to be very different from those of bulk Bi.

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