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Van der Pauw method

About: Van der Pauw method is a research topic. Over the lifetime, 1682 publications have been published within this topic receiving 25364 citations.


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Journal ArticleDOI
TL;DR: A vacuum-insulated thermostat capable of measuring the thermoelectric properties of thin films from room temperature to 850 K and in-plane electrical conductivity measurement is accomplished at high speed to avoid possible Seebeck voltage effect on van der Pauw measurements.
Abstract: We have designed and fabricated a vacuum-insulated thermostat capable of measuring the thermoelectric properties of thin films from room temperature to 850 K. High speed Seebeck voltage transients are resolved to 200 ns with 63 dB dynamic range in order to directly measure thermoelectric device figure of merit. In-plane Seebeck coefficient probes measure voltage and temperature difference at identical locations with low parasitic contributions. In-plane electrical conductivity measurement is accomplished at high speed to avoid possible Seebeck voltage effect on van der Pauw measurements.

20 citations

Journal ArticleDOI
TL;DR: The results of this work enable epitaxial growth of gallium oxide thin films, with superior material properties offered by ALD, not only with potential applications as a high-performance material in reducing global energy consumption but also with an energy efficient fabrication process.
Abstract: This work explores the applicability of atomic layer deposition (ALD) in producing highly oriented crystalline gallium oxide films on foreign substrates at low thermal budgets. The effects of substrate, deposition temperature, and annealing process on formation of crystalline gallium oxide are discussed. The Ga2O3 films exhibited a strong preferred orientation on the c-plane sapphire substrate. The onset of formation of crystalline gallium oxide is determined, at which only two sets of planes, i.e., α-Ga2O3 (006) and β-Ga2O3 (402), are present parallel to the surface. More specifically, this work reports, for the first time, that epitaxial gallium oxide films on sapphire start to form at deposition temperatures ≥ 190 °C by using an optimized plasma-enhanced ALD process such that α-Ga2O3 (006)∥α-Al2O3 (006) and β-Ga2O3 (201)∥α-Al2O3 (006). Both α-Ga2O3 (006) and β-Ga2O3 (201) planes are polar planes (i.e., consisting of only one type of atom, either Ga or O) and, therefore, favorable to form by ALD at such low deposition temperatures. Ellipsometry and van der Pauw measurements confirmed that the crystalline films have optical and electrical properties close to bulk gallium oxide. The film grown at 277 °C was determined to have superior properties among as-deposited films. Using TEM to locate α-Ga2O3 and β-Ga2O3 domains in the as-deposited crystalline films, we proposed a short annealing scheme to limit the development of α-Ga2O3 domains in the film and produce pure β-Ga2O3 films via an energy-efficient process. A pure β-Ga2O3 phase on sapphire with β-Ga2O3 (201)∥α-Al2O3 (006) was successfully achieved by using the proposed process at the low annealing temperature of 550 °C preceded by the low deposition temperature of 190 °C. The results of this work enable epitaxial growth of gallium oxide thin films, with superior material properties offered by ALD, not only with potential applications as a high-performance material in reducing global energy consumption but also with an energy-efficient fabrication process.

20 citations

Journal ArticleDOI
20 Sep 2018-Sensors
TL;DR: The results establish the aptness of the as-grown CNT film to be used as an active sensing material in thin film temperature sensors.
Abstract: In this paper, we present the fabrication of an efficient thin film temperature sensor utilizing chemical vapor deposited carbon nanotube (CNT) film as the sensing element on Si substrates, with diamond-like carbon (DLC):Ni as a catalyst in assisting CNT growth. The fabricated sensor showed good electrical response with change in temperature. Relative linear change in resistance of 18.4% for an increase in temperature from 22 °C to 200 °C was achieved. Various characterizing techniques, such as scanning electron microscopy (SEM) and Raman spectroscopy, were used to characterize the films. In an effort to study device performance, van der Pauw and Hall measurements were carried out to study the dependence of resistance on temperature and magnetic fields. Temperature coefficient of resistance of the sensor was calculated as 1.03 × 10-3/°C. All implications arising from the study are presented. The results establish the aptness of the as-grown CNT film to be used as an active sensing material in thin film temperature sensors.

20 citations

Journal ArticleDOI
TL;DR: In this paper, the transport and structural properties of (La,Sr)TiO3 epitaxial thin films grown by pulsed-laser deposition are investigated and shown to be a viable candidate as a conducting buffer for superconducting film growth on biaxially textured metal tapes.
Abstract: The transport and structural properties of (La,Sr)TiO3 epitaxial thin films grown by pulsed-laser deposition is presented. In particular, the potential use of (La,Sr)TiO3 as a conductive buffer layer for subsequent growth of high temperature superconducting films for coated conductors is discussed. Van der Pauw measurements of film resistivity as a function oxidation conditions show that, for undoped LaTiO3 films, the resistivity increases rapidly as background oxygen pressure is increased, which is consistent with the formation of the LaTiO3þx phase. Sr doping of LaTiO3 significantly enhances the conductivity of thin film materials when synthesized under oxidizing conditions. The transport behavior for Sr-doped LaTiO3 films correlates with structural data showing no significant shift in lattice spacing as oxygen partial pressure is increased during film growth. In addition, the epitaxial growth of (La,Sr)TiO3 on biaxially textured Ni alloy tapes is demonstrated. These results suggest that (La,Sr)TiO3 is a viable candidate as a conducting buffer for superconducting film growth on biaxially textured metal tapes. � 2003 Elsevier Ltd. All rights reserved.

20 citations

Journal ArticleDOI
04 Jun 1996
TL;DR: In this article, a four-electrode conductance cell designed and used according to the van der Pauw method can be applied for the absolute determination of the electrolytic conductivity of solutions with an accuracy comparable with that of the secondary standards for this quantity.
Abstract: It appears that a four-electrode conductance cell designed and used according to the van der Pauw method can be applied for the absolute determination of the electrolytic conductivity of solutions with an accuracy comparable with that of the secondary standards for this quantity. Therefore there may be a possibility of avoiding the use of those standards in some cases. The results of the experimental investigation of a prototype model of the cell of this type, carried out by the authors, are consistent with the theoretical considerations and computer modeling. An absolute determination of electrolytic conductivity has been made for 0.01 and 0.1 M KCl solutions, with an overall uncertainty lower than 0.4%.

20 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202328
202241
202128
202030
201960
201867