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.

Characterization of cadmium telluride thin films fabricated by two-source evaporation technique and Ag doping by ion exchange process

Abstract: Cadmium telluride (CdTe) thin films were deposited onto scratch free transparent glass substrates by two-source evaporation technique, using Cd and Te as two different evaporants. In the next step films were heated under vacuum at 400 °C for 1 h and dipped in AgNO 3 –H 2 O solution at room temperature. These films were again heated under vacuum for 1 h at 400 °C to obtain maximum Ag diffusion. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), electrically i.e. DC electrical resistivity by van der Pauw method at room temperature, dark conductivity, activation energy analysis as a function of temperature by two-probe method under vacuum and optically by Lambda 900 UV/VIS/NIR spectrophotometer. The EDX results showed an increase of Ag content in the samples by increasing immersion time of the CdTe films in the solution.

The effect of dislocations on the transport properties of III/V-compound semiconductors on Si

Abstract: The transport properties of InP and GaAs epitaxial layers grown on exactly (001)‐oriented Si substrates were investigated by temperature‐dependent van der Pauw measurements combined with anodic stripping. Electron concentrations n at T=300 K decreasing from around 1018 cm−3 at the heterointerface to a constant level of 1016 cm−3 toward the surface agree well with the concentration profile of Si donors. Their activation energy is 2.9 and 1.3 meV in InP/Si and GaAs/Si, respectively. At low temperatures a marked decrease of the electron mobility μ at the heterointerface occurred. A quantitative analysis of μ (T) led to the model of charged dislocations as scattering centers. By comparison with the dislocation densities of 2×108 and 1×108 cm−2 in the vicinity of the surface of 2‐ and 3‐μm‐thick layers found by wet chemical etching we derived the occupation probability of the charged centers along the dislocation lines as 0.2 and 1.0 for InP and GaAs, respectively. At 300 K μ was almost unaffected by dislocati...

A novel limiting current oxygen sensor prepared by slurry spin coating

Abstract: La0.7Sr0.3MnO3 (LSM) and Y0.08Zr0.92O2 (8YSZ) were synthesized by citric-nitrate and co-precipitation methods, respectively. Crystal structure and conductivity of the samples were characterized by X-ray diffraction (XRD) and DC van der Pauw measurements, respectively. A limiting current oxygen sensor was fabricated with 8YSZ solid electrolyte and LSM dense diffusion barrier by a slurry spin coating method. The process parameters and sensing performances were investigated. Results: LSM is perovskite structure. The total conductivity of LSM is 104.95–162.18 S·cm−1 from 300 to 800 °C. The obtained optimum process parameters of slurry spin coating are: ethyl cellulose content of 3 wt%, coating cycle number of 7 and sintering temperature of 1400 °C. The sensor exhibits a good limiting current plateau that depends linearly on the oxygen concentration, and exponentially on the reciprocal temperature.

Growth studies of pseudomorphic GaAs/InGaAs/AlGaAs modulation‐doped field‐effect transistor structures

Abstract: Strained GaAs/InGaAs/AlGaAs quantum well structures have been grown by molecular beam epitaxy at substrate temperatures from 375 to 510 °C. The well layer thickness and In composition are analyzed by ion channeling and particle‐induced x‐ray emission as a function of growth temperature. Test structures for modulation‐doped field‐effect transistors grown at 375 and 510 °C under two different As4 overpressures were also characterized by Van der Pauw measurements and low‐temperature photoluminescence. The observed differences in film quality can be explained by the influence of substrate temperature and As4 flux on the cation surface mobility during growth of the InGaAs layer.

Doping of silicon by phosphorus end-terminated polymers: drive-in and activation of dopants

Abstract: An effective doping technology for the precise control of P atom injection and activation into a semiconductor substrate is presented. Polystyrene polymers with a narrow molecular weight distribution and end-terminated with a P containing moiety are used to build up a phosphorus δ-layer to be used as the dopant source. P atoms are efficiently injected into the Si substrate by high temperature (900–1250 °C) thermal treatments. Temperature dependent (100–300 K) resistivity and Hall measurements in the van der Pauw configuration demonstrate high activation rates (ηa > 80%) of injected P atoms. This bottom-up approach holds promise for the development of a mild technology for efficient doping of semiconductors.