Topic
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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TL;DR: In this paper, the van der Pauw-Hall measurement was used to evaluate the electrical transport performance of graphene by annealing graphene in vacuum to remove the adsorbed dopants and then exposing it in ambient surroundings.
Abstract: Expected for many promising applications in the field of electronics and optoelectronics, a reliable method for the characterization of graphene electrical transport properties is desired to predict its device performance or provide feedback for its synthesis. However, the commonly used methods of extracting carrier mobility from graphene field effect transistor or Hall-bar is time consuming, expensive, and significantly affected by the device fabrication process other than graphene itself. Here we reported a general and simple method to evaluate the electrical transport performance of graphene by the van der Pauw–Hall measurement. By annealing graphene in vacuum to remove the adsorbed dopants and then exposing it in ambient surroundings, carrier mobility as a function of density can be measured with the increase of carrier density due to the dopant re-adsorption from the surroundings. Further, the relationship between the carrier mobility and density can be simply fitted with a power equation to the first level approximation, with which any pair of measured carrier mobility and density can be normalized to an arbitrary carrier density for comparison. We experimentally demonstrated the reliability of the method, which is much simpler than making devices and may promote the standard making for graphene characterization.
14 citations
TL;DR: Copper coated nickel foam with Cu/Ni ratio of 2.5 was fabricated using electrochemical plating and characterized using XRD, SEM, EDS and Van der Pauw four point conductivity measurements as mentioned in this paper.
14 citations
TL;DR: In this article, the electrical behavior of zinc ions implanted into chromium-doped semi-insulating gallium arsenide was investigated by measurements of the sheet resistivity and Hall effect.
Abstract: The electrical behavior of zinc ions implanted into chromium-doped semiinsulating gallium arsenide was investigated by measurements of the sheet resistivity and Hall effect Room temperature implantations were performed using fluence values from 10 to the 12th to 10 to the 15th power/sq cm at 60 keV The samples were annealed for 30 minutes in a nitrogen atmosphere up to 800 C in steps of 200 C and the effect of this annealing on the Hall effect and sheet resistivity was studied at room temperature using the Van der Pauw technique The temperature dependence of sheet resistivity and mobility was measured from liquid nitrogen temperature to room temperature Finally, a measurement of the implanted profile was obtained using a layer removal technique combined with the Hall effect and sheet resistivity measurements
14 citations
TL;DR: The electrical resistance tomography (ERT) technique is applied to the measurement of sheet conductance maps of both uniform and patterned conductive thin films as mentioned in this paper. But this technique is not suitable for high dimensional data.
Abstract: The electrical resistance tomography (ERT) technique is applied to the measurement of sheet conductance maps of both uniform and patterned conductive thin films. Images of the sheet conductance spatial distribution and local conductivity values are obtained. Test samples are tin-oxide films on glass substrates, with electrical contacts on the sample boundary. Some samples are deliberately patterned in order to induce null conductivity zones of known geometry, while others contain higher conductivity inclusions. Four-terminal resistance measurements among the contacts are performed with a scanning setup. The ERT reconstruction is performed by a numerical algorithm based on the total variation regularization and the $L$ -curve method. ERT correctly images the sheet conductance spatial distribution of the samples. The reconstructed conductance values are in good quantitative agreement with independent measurements performed with the van der Pauw and the four-point probe methods.
14 citations
TL;DR: In this article, the authors proposed to activate arsenic as a p-type dopant at temperatures sufficiently low that they will not compromise the integrity of p-n junctions and showed that the energy barrier for As transfer from Hg to Te sites can be overcome at 250°C.
Abstract: The HgCdTe infrared detectors and test structures based on dual or multicolor HgCdTe are desirable for various applications. It is important to control both pand n-type extrinsic doping in these photovoltaic structures. This paper addresses the issue of activating arsenic as a p-type dopant at temperatures sufficiently low that they will not compromise the integrity of p-n junctions. Midwavelength infrared (MWIR) HgCdTe epilayers were grown by molecular beam epitaxy (MBE) using an In-free type of mounting. The doping was performed by coevaporating arsenic from an elemental solid source during the growth. During postgrowth treatments, we employed a two-step annealing process. During both steps, we used temperatures (300°C, 275°C, and 250°C) that are well below the current standard annealing temperatures. The results suggest that the energy barrier for As transfer from Hg to Te sites can be overcome at 250°C; hence, p doping can be achieved at the temperature of 250°C. The temperature-dependent Hall effect characteristics of the grown samples were measured by the van der Pauw technique with magnetic fields up to 0.4 T.
14 citations