Papers by Keyword: Resistivity

Abstract: A conventional way to determine precipitation kinetics in heat treatable aluminium alloys is to monitor the associated solute loss by in-situ resistivity. A Gleeble machine is used to perform so called isothermal quenching (IQ) resistivity measurements. IQ consists in quenching the alloy down to a given temperature and holding it at this temperature. The results are validated against measurements performed with a classical four-points method using continuous current on the same alloy.

Abstract: Geothermal energy is an important type of renewable energy. It can be easily mined at low cost, and has the advantages of no pollution and recycling utilization. The exploitation of geothermal energy can bring about significant economic, social and environmental benefits. The base for geothermal energy exploitation is the exploration of geothermal field. Analysis of the geological background of regional structure and heat control, collect adjacent areas geological data in Inner Mongolia with the use of electromagnetic sounding.

Abstract: In the work, the resistivity of the SiN film was discussed, the resistivity of the SiN film was influenced by the deposition parameters, such as the sputtering power, deposition temperature, N₂ pressure and ratio of N₂/(N₂+Ar). Only considering the resistivity of the SiN film, the optimal parameters of the film were as below, the sputtering power was 50W, the substrate temperature was 400°C, N₂ pressure was 1Pa, and the ratio of N₂/(N₂+Ar) was 2.5%.

Abstract: Deoxyribonucleic acid (DNA), as the most important molecule in nature, holds promise as a key element of the molecular electronics as its utilization in the synthesis of electronic devices such as micro and nanosensors has increased remarkably during the recent years. Our work is devoted to an experimental study of the electrical resistivity of a gold-DNA-gold (GDG) structure in the presence of a variable external magnetic field. The DNA strands, extracted by the PCR method, were used to fabricate the GDG structures. The resistivity of the structure was found to rise sharply with the magnitude of the exerted magnetic field due to onset and progression of the cyclotron effects in charge carriers. Such a distinct current-voltage signature can possibly be employed for realization of an accurate magnetic sensor.

Abstract: To study the grouting detection standard of Karst roadbed based on resistivity method, transient Surface wave method and electromagnetic wave CT, the typical test areas in the Karst roadbed of NANNING-GUANGZHOU railway are selected, and the field test research of grouting detection standard of Karst roadbed was studied by the above three geophysical methods. The grouting qualified Karst roadbed was determined by multiple methods of borehole coring and field water pressure after grouting, and the test results of Karst roadbed grouting qualified was confirmed effective sample. The difference value of resistivity, surface wave velocity and electromagnetic wave absorption coefficient of limestone layer, clay, pebble soil and Karst cave was statistical analyzed based on the effective test data, and preliminarily obtained the detection standard of Karst roadbed grouting effect based on the above three geophysical methods.

Abstract: Thin films of gallium nitride (GaN) and related nitride materials were prepared, and their properties as transparent conducting electrodes were investigated. GaN thin films were directly grown on sapphire single crystal substrates by the molecular beam epitaxy. Heavy doping of germanium was employed to reduce resistivity of the films, with sufficient reduction found to be possible while maintaining their epitaxial growth state. Optical transmission spectra of the films in the short wavelength region were slightly deteriorated by the heavy doping; however, this was successfully improved by growing GaN films under metal-rich conditions to increase the electron mobility and suppress unwanted increase of the carrier densities. In addition, the optical transmission spectra in the short wavelength region was improved also by alloying GaN with aluminum nitride, though the resistivities of these films were relatively higher than those of the unmodified GaN films. The prepared nitride thin films exhibited sufficiently suitable properties as transparent conducting electrodes for use in applications such as full-spectrum nitride-based solar cells.

Abstract: This paper reports the results of investigation into the effects of annealing on microstructure, hardness, and electrical resistivity of accumulated drawing and bundling (ADB) Cu-Nb wires. Noticeable change took place during annealing. When annealing was conducted at 500 °C, samples showed higher hardness and electrical resistivity in the wires with higher deformation. Furthermore, samples annealed at temperatures above 500 °C showed delay in recovery and recrystallization. At 900 °C, however, the reverse was true, with samples showing lower hardness and resistivity in wire with higher degree of deformation.

Abstract: The aim of this work is to study the low temperature annealing effect on the electrical properties of p-type multicrystalline silicon grown by Heat Exchanger Method (HEM).The minority carrier lifetime variation, the transition metal elements behavior, the sheet resistivity and the interstitial oxygen concentration after different temperatures annealing under N₂ ambient were investigated using quasi-steady state photoconductance technique (QSSPC), secondary ion mass spectroscopy (SIMS), four-probe measurement and Fourier transform infrared spectrometer (FTIR), respectively. The obtained results indicate in the temperature range of 300°C to 700°C that the effective lifetime increases and reaches its maximum values of 28 μs at 500 °C and decreasing to 6 μs at 700 °C. This amelioration is due probably to metallic impurities internal gettering in the extended defects and in the oxygen precipitates as observed on SIMS profiles and the FTIR spectra. From 300 °C to 500 °C the sheet resistivity values rest unchanged at 30 Ω.cm^-2 and rises significantly to reach 45 Ω.cm^-2 for T> 500 °C.

Abstract: Aluminium doped zinc oxide (AZO) is fast becoming an important thin film material for applications as transparent conducting oxide (TCO) in several thin film solar cells, smart windows and many devices using touch screen displays. This is due to its good electrical and optical characteristics as well as lower cost and good abundance. Although sputtering is the general method for industrial fabrication of this material, but film characteristics depend strongly on fabrication processes. Thus, optimal films are obtained by optimization of the deposition conditions. In this work, we investigated the effects of RF deposition power on AZO thin films. Samples of similar thicknesses were grown under similar conditions in an RF sputtering chamber at different RF powers. The samples were then characterized using FESEM, AFM, UV-Vis, XRD and Hall effect measurement tools. Results indicate that the surface morphology is slightly affected with larger grain sizes obtained at higher RF powers. Also the surface roughness, average transmittance, conductivity and deposition rate all increase with the RF power. The lowest as-deposited resistivity of 15.3x10^-3 Ω/cm was obtained, at the highest RF power of 100 W. This film also have the highest values of carrier concentration, mobility and figure of merit of 4.24x10²⁰ cm^-3, 0.96 cm²/V and 0.27x10^-3 Ω respectively. This work highlights the significance of RF power in the fabrication of good quality AZO thin films.

Abstract: Inspection and measurement for the sheet resistance and resistivity play a pivotal role in the semiconductor industry. In this study, a high-accuracy measurement system for sheet resistance of thin films was designed based on dual-measurement with four-point probe method. The measurement system was composed of a special switching circuit, a digital output module, Keithley 2400 SourceMeter, and a computer running LabVIEW. The special switching circuit designed based on the multiplexer played an important role in current probes and voltage probes automatic switching under the control of virtual instrumentation software LabVIEW and National instruments digital output module hardware NI 9401. Keithley 2400 SourceMeter controlled by LabVIEW was used for two-times high-precision voltage measurement. Van der Pauw correction factor were calculated based on the results of the two-times voltage measurement. Then the sheet resistance of thin films was calculated by LabVIEW softwares powerful computing. The experimental results show that the designed and developed system can meet the needs of fast on-line measurement of thin films sheet resistance with a wide range, and moreover, the accuracy of measurements and the level of automatization have been dramatically improved compared to the conventional measurement system.