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.

Sheet Resistance Measurement of Inkjet Printed Layers

Abstract: The Van der Pauw method is a method commonly used to measure the resistance and Hall coefficient of a sample. Its advantage lies in its ability to accurately measure the properties of a random sample, ensuring that the sample is approximately two-dimensional (i.e., it is much thinner than it is wide), rigid (without holes), and the electrodes are located on the perimeter. The Van der Pauw method uses a 4-point probe around the sample circumference, unlike the linear 4-point probe: this allows the Van der Pauw method to provide a mean resistance of the sample while the linear array provides resistance in the reading direction. [1] This difference becomes important for anisotropic materials, which can be correctly measured by the various modifications of the Van der Pauw method.

Low temperature synthesis of α- and β-phase Bi2O3 thin film via B doping: tailoring optical band gap and n- to p-type Bi2O3

Abstract: In this article, we fabricated p-type bismuth oxide (Bi2O3) thin films with tailoring optical band gap by boron (B) doping, for the first time. In addition, an effort is made to see the influence of B doping on the surface morphological, structural, optical and electrical transport properties of Bi2O3 thin films. Field Emission Scanning Electron Microscope (FESEM) images demonstrated that the film surface is covered by well-defined multigonal shaped particles and glassy surface. α-Bi2O3 (monoclinic) and β-Bi2O3 (tetragonal) phase structures are confirmed by X-ray diffraction (XRD) analysis. The average crystallite size is decreased from 46.62 to 23.57 nm with B doping concentration. Moreover, the average strain, stress and dislocation density values are calculated using XRD data. The optical band gaps have changed from 3.70 to 3.99 eV with the texture coefficient values of $$ \left( {11\bar{2}} \right) $$ orientation plane. A minimum refractive index and optical conductivity value are found to be 2.58 and 2.23 × 106 Ω−1 m−1 for 3 at.% B content. Electrical parameters, viz. resistivity, sheet resistance, charge carrier concentration, mobility and conductivity types are investigated using a van der Pauw Hall measurement system. Electrical measurements demonstrated that the resistivity values are found to vary in the range of 1.23–1.82, × 103 Ω-m with increasing B doping concentrations. A high-quality factor is obtained 5.52 × 10−6 Ω−1 for higher doping content at 550 nm wavelength. This work promotes a new vision into the fabrication of p-type Bi2O3 thin films and facilitates their application in the field of optoelectronic devices, viz. window layer coating, p–n junction and photovoltaic applications.

Nondestructive evaluation of channel carrier concentration in modulation-doped InAlAs/InGaAs field-effect transistor structures by room-temperature photoluminescence

Abstract: The sheet carrier concentration (Ns) of channel layers in modulation-doped InAlAs/InGaAs heterostructure field-effect transistor (HFET) structures with n+InGaAs contact layers has been successfully and nondestructively determined using the room-temperature photoluminescence (PL) method. It is found that the spectral energy width between the maximum position of the main PL peak around 0.8 eV and the half-maximum position on the higher energy side has a good positive linear correlation with the Ns of the channel measured by the van der Pauw method. The scattering of the data is less than ±3×1011 cm−2. The determination of Ns is effective even if the HFET structures have not only n+InGaAs contact layers but also layers for InAlAs Schottky level-shift diodes. From a comparison with low-temperature PL spectra, the main PL peak is attributed to the e2h transition in the quantum well of the channel. It is considered that the slope of the peak stretches further to the high energy as the Fermi energy in the channe...

Measurement of the variable surface charge concentration in gallium nitride and implications on device modeling and physics

Abstract: We have evaluated the density of interface trap states (Dit) at the surface of a GaN/AlGaN/GaN heterojunction by the previously described gated van der Pauw experiments, as well as by a UV assisted gated van der Pauw method, described in this article. The obtained Dit values are about two orders of magnitude lower than assumed by the surface-donor theory and three orders of magnitude lower than required to compensate the polarization surface charge in GaN. Previous experimental studies using a variety of other techniques reported similarly low Dit values. We hence conclude that variable midgap surface-charge is not responsible for the formation of the two-dimensional electron gas, and cannot compensate for the large surface polarization charge in GaN. A yet unexplained polarization self-compensating (PSC) surface charge must be invoked to account for experiments. A few comments about the physical nature of the proposed PSC charge are provided.

Hole mobility in aluminium implanted silicon

Abstract: The dependence of the hole mobility on the dopant concentration ranging from to was determined at room temperature in Al-implanted Si samples The trend was obtained by the use of Hall effect and resistivity measurements on the van der Pauw pattern in combination with secondary-ion mass spectrometry and spreading resistance analysis The mobility data are in a quite good agreement with the Wagner curve for boron in the high Al concentration region while they approach the Thurber boron curves at low concentrations This result indicates that the neutral and ionized impurity scattering mechanisms are not critically different for Al- and B-doped samples The mobility - dopant concentration curve can be employed to convert the resistivity profiles obtained by spreading resistance measurements into hole concentration distributions for Al-doped samples