High Temperature Variable Range Hopping in Heavy Al Implanted 4H-SiC

2016 ◽  
Vol 858 ◽  
pp. 283-286 ◽  
Author(s):  
Antonella Parisini ◽  
Andrea Parisini ◽  
Marco Gorni ◽  
Roberta Nipoti
Keyword(s):  
Electrical Transport ◽  
Room Temperature ◽  
Hole Transport ◽  
Variable Range Hopping ◽  
Electrical Transport Properties ◽  
Hopping Transport ◽  
Variable Range ◽  
Transmission Electron ◽  
Temperature Variable ◽  
Post Implantation

In this work, we confirm and extend the results of a previous study where a variable range hopping transport through localized impurity states has been found to dominate the electrical transport properties of 3×1020 cm-3 and 5×1020 cm-3 Al+ implanted 4H-SiC layers after 1950-2000 °C post implantation annealing. In this study, samples with longer annealing times have been taken into account. The temperature dependence of these sample conductivity follows a variable range hopping law, consistent with a nearly two-dimensional hopping transport of non-interacting carriers that in the highest doped samples, persists up to around room temperature. This result indicates that the hole transport becomes strongly anisotropic on increasing the doping level. At the origin of this unusual electrical behavior, may be the presence of basal plane stacking faults, actually observed by transmission electron microscopy in one of the 5×1020 cm-3 samples

scholarly journals Electrical Transport Properties ofNi95Ti5Catalyzed Multi wall Carbon Nanotubes Film

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
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.

scholarly journals Electrical Properties of Polytypic Mg Doped GaAs Nanowires

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
N. Cifuentes ◽  
E. R. Viana ◽  
H. Limborço ◽  
D. B. Roa ◽  
A. Abelenda ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Field Effect Transistors ◽  
Variable Range Hopping ◽  
Transport Parameters ◽  
Electrical Transport Properties ◽  
Variable Range ◽  
Gaas Nanowires ◽  
P Type ◽  
Mg Doped ◽  
Variable Range Hopping Conduction

The electrical transport properties of individual Mg doped GaAs nanowires are investigated. It is shown that Mg can be successfully used as a nontoxic p-type dopant in GaAs nanowires. The doping levels, expanding over two orders of magnitude, and free holes mobility in the NW were obtained by the analysis of field effect transistors transfer curves. The temperature dependence of the electrical resistivity above room temperature shows that the polytypic structure of the NWs strongly modifies the NWs charge transport parameters, like the resistivity activation energy and holes mobility. At lower temperatures the NWs exhibit variable range hopping conduction. Both Mott and Efros-Shklovskii variable range hopping mechanisms were clearly identified in the nanowires.

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

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

Observation of the Wurtzite Phase in OMVPE Grown ZnSe/GaAs: Effect on Implantation and Rapid Thermal Annealing

1989 ◽  
Vol 147 ◽  
Author(s):  
K. S. Jones ◽  
J. Yu ◽  
P. D. Lowen ◽  
D. Kisker
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Electrical Transport ◽  
High Resistivity ◽  
Ion Milling ◽  
Electrical Transport Properties ◽  
Wurtzite Phase ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Diffraction Patterns

AbstractTransmission electron diffraction patterns of cross-sectional TEM samples of OMVPE ZnSe on GaAs indicate the existence of the hexagonal wurtzite phase in the epitaxial layers. The orientation relationship is (0002)//(111); (1120)//(220). Etching studies indicate the phase is internal not ion milling induced. The average wurtzite particle size is 80Å-120Å. Because of interplanar spacing matches it is easily overlooked. Electrical property measurements show a high resistivity (1010ω/square) which drops by four orders of magnitude upon rapid thermal annealing between 700°C and 900 °C for 3 sec. Implantation of Li and N have little effect on the electrical transport properties. The Li is shown to have a high diffusivity, a solid solubility of ≈1016/cm3 at 800°C and getters to the ZnSeA/aAs interface.

Reinvestigation the Thermal and Electrical Transport Properties of Tl7Sb2

2013 ◽  
Vol 802 ◽  
pp. 284-288
Author(s):  
Anek Charoenphakdee ◽  
Adul Harnwangmuang ◽  
Tosawat Seetawan ◽  
Chesta Ruttanapun ◽  
Vittaya Amornkitbamrung ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Transport Properties ◽  
Electrical Transport ◽  
Room Temperature ◽  
Lattice Parameter ◽  
Electronic Contribution ◽  
Electrical Transport Properties ◽  
Space Group ◽  
Crystal System ◽  
Thallium Compounds

The authors examined the thermal and electrical transport properties of Tl7Sb2 at temperatures ranging from room temperature to 400 K. The crystal system of Tl7Sb2 is cubic with the lattice parameter a = 1.16053 nm and the space group is Im3m. The polycrystalline samples were prepared by melting stoichiometric amounts of thallium and antimony. Although, usually the thermal conductivity of thallium compounds is very low (<1 Wm-1K-1), that of Tl7Sb2 was relatively high (~13 Wm-1K-1 at room temperature). This is because of the large electronic contribution to the thermal conductivity.

Electrical Transport Properties of the Pentatelluride Materials Hfte5 and Zrte5

1997 ◽  
Vol 478 ◽  
Author(s):  
T. M. Tritt ◽  
M. L. Wilson ◽  
R. L. Littleton ◽  
C. Feger ◽  
J. Kolis ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Electrical Transport ◽  
Entire Range ◽  
Room Temperature ◽  
Polycrystalline Material ◽  
Polycrystalline Materials ◽  
Electrical Transport Properties ◽  
Low Dimensional ◽  
P Type

AbstractWe have measured the resistivity and thermopower of single crystals as well as polycrystalline pressed powders of the low-dimensional pentatelluride materials: HfTe5 and ZrTe5. We have performed these measurements as a function of temperature between 5K and 320K. In the single crystals there is a peak in the resistivity for both materials at a peak temperature, Tp where Tp ≈ 80K for HfTe5 and Tp ≈ 145K for ZrTe5. Both materials exhibit a large p-type thermopower around room temperature which undergoes a change to n-type below the peak. This data is similar to behavior observed previously in these materials. We have also synthesized pressed powders of polycrystalline pentatelluride materials, HfTe5 and ZrTe5. We have measured the resistivity and thermopower of these polycrystalline materials as a function of temperature between 5K and 320K. For the polycrystalline material, the room temperature thermopower for each of these materials is relatively high, +95 μV/K and +65 μV/K for HfTe5 and ZrTe5 respectively. These values compare closely to thermopower values for single crystals of these materials. At 77 K, the thermopower is +55 μV/K for HfTe5 and +35 μV/K for ZrTe5. In fact, the thermopower for the polycrystals decreases monotonically with temperature to T ≈ 5K, thus exhibiting p-type behavior over the entire range of temperature. As expected, the resistivity for the polycrystals is higher than the single crystal material, with values of 430 mΩ-cm and 24 mΩ-cm for Hfre5 and ZrTe5 respectively, compared to single crystal values of 0.35 mΩ-cm (HfTe5) and 1.0 mΩ-cm (ZrTe5). We have found that the peak in the resistivity evident in both single crystal materials is absent in these polycrystalline materials. We will discuss these materials in relation to their potential as candidates for thermoelectric applications.

New Compounds Consisting of Turbostratic Intergrowths: Ultra-low Thermal Conductivities and Tunable Electric Properties

2011 ◽  
Vol 1329 ◽  
Author(s):  
Matt Beekman ◽  
Daniel B. Moore ◽  
Ryan Atkins ◽  
Colby Heideman ◽  
Qiyin Lin ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Scanning Transmission Electron Microscopy ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Transmission Electron ◽  
Plane Component ◽  
Structural Space ◽  
Scanning Transmission ◽  
New Compounds ◽  
Film Form

ABSTRACTA recently discovered synthetic route to new kinetically stable [(MSe)y]m[TSe2]n layered intergrowths has been applied to prepare several different compositions (M = Pb or Sn, T = Ta, Nb, Mo, or W) with m = n = 1, in thin film form. Scanning transmission electron microscopy and synchrotron X-ray diffraction show the nanostructure of these materials is characterized by a combination of in-plane component crystallinity with misregistration and rotational mis-orientation between adjacent layers. Extremely low cross-plane thermal conductivity as low as 0.1 W m-1 K-1 are attributed to the turbostratic nanostructure. By appropriate choice of M and T, we demonstrate that a range of electrical transport properties are possible, from metallic to semiconducting. Annealing (PbSe)0.99WSe2 and (PbSe)1.00MoSe2 specimens in a controlled atmosphere of PbSe or WSe2 is observed to systematically influence carrier properties, and is interpreted in terms of reduction of the concentration of electrically active defects. Considering these observations and the large composition and structural space that can be explored in such [(MSe)y]m[TSe2]n intergrowths, these materials are of interest for further investigation as potential thermoelectric materials.

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