China
Africa
Explore chapters and articles related to this topic
Introduction to Semiconductor Physics
Published in Lev I. Berger, Semiconductor Materials, 2020
The van der Pauw method2.6 is based on formation of four (or more) point contacts along the circumference of an arbitrarily shaped (but uniform in thickness) sample, provided that the sample does not have isolated holes through it If the contacts form a sequence A, B, C, and D, the test procedure consists of formation of a current IAB between the contacts marked A and B and measurement of voltage drop VDC between the contacts C and D; then the current is formed between contacts B and C (IBC), and voltage drop is measured between contacts D and A (VDA). Denoting VCIAB = RAB,CD and VDA/IBC- = RBC,DA, one may calculate the volume resistivity of the sample as
Tungsten Disulfide Polythiophene Nanocomposites
Published in Mahmood Aliofkhazraei, Advances in Nanostructured Composites, 2019
Nicole Arsenault, Rabin Bissessur, Douglas C. Dahn
Another technique used to determine the conductivity is the van der Pauw method (van der Pauw 1958). It uses four point contacts attached at the edge of the sample as shown in Figure 6. The sample can be any shape, but must be thin, homogeneous and of uniform thickness t. The contacts need not be evenly spaced. Two resistances Ra and Rb are determined by measuring the voltage between two adjacent contacts while current is passed through the sample via the other two contacts, as described in more detail below. The resistivity (ρ) of the sample is then found by solving the van der Pauw Eq. 3. () e−πRatρ+e−πRbtρ=1
Experimental Considerations of 2D Graphene
Published in Andre U. Sokolnikov, Graphene for Defense and Security, 2017
The van der Pauw, method used for these measurements, is a classical approach for measuring resistivity and the Hall coefficient. The advantage of this technique is in the feasibility of measuring a sample of an arbitrary shape. The sample must be two-dimensional and solid. The electrodes are installed as in Fig. 8.30 a) used for these measurements. The current I2,6 is measured between 2 and 6. The parallel terminals 3 and 5 are displaced by the distance L. The resistance RNL is calculated from the measured voltage between 3 and 545. () RNL=V3,5/I2,8∝ρxxexp(−πL/ω);
Low-resistivity oxides in TixFeCoNi thin films after vacuum annealing
Published in Surface Engineering, 2018
Ya-Chu Yang, Chun-Huei Tsau, Jien-Wei Yeh, Swe-Kai Chen
The electrical properties of the resulting alloys were characterised using a Hall-effect measurement system (HL5500PC) and a four-point-probe system (Napson Corp. Model TR-70). The specimens for both measurements have dimensions of about 10 × 10 × 0.5 mm. Hall-effect measurements were performed with van der Pauw method at room temperature. Linear four-point-probe setup with uniform 1 mm probe spacing was employed to measure the resistivity of thin films at room temperature. Five measurements were done on each specimen for obtaining an average. The microstructural morphology of the films was examined using a field-emission scanning electron microscope (FESEM, JSE-6500F, JEOL). The phases of the thin films were identified using an X-ray diffractometer (XRD, Rigaku TTRAX III) with glancing angle of 1.5 degrees. The microstructure and composition of the films were investigated using a transmission electron microscope (TEM, JEM-3000F, JEOL) with an energy dispersive spectrometer (EDS). The TEM specimens were taken from the films using a dual-beam focused ion beam microscope (DB-FIB, FEI Nova-200). The dimensions are about 10 × 3 μm in size and 150 nm thick.