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.

TEMPERATURE PROGRAMMED DESORPTION OF F-DOPED SnO2 FILMS DEPOSITED BY INVERTED PYROSOL TECHNIQUE

Abstract: Fluorine-doped tin dioxide (FTO) films were deposited on silicon wafers by inverted pyrosol technique using solutions with different doping concentration (F/Sn=0.00, 0.12, 0.75 and 2.50). The physical and electrical properties of the deposited films were analyzed by SEM, XRF, resistivity measurement by four-point-probe method and Hall coefficient measurement by van der Pauw method. The electrical properties showed that the FTO film deposited using the solution with F/Sn=0.75 gave a lowest resistivity of 3.2·10–4 ohm cm. The FTO films were analyzed by temperature programmed desorption (TPD). Evolved gases from the heated specimens were detected using a quadruple mass analyzer for mass fragments m/z, 1(H+), 2(H2+), 12(C+), 14(N+), 15(CH3+), 16(O+), 17(OH+ or NH3+), 18(H2O+ or NH4+), 19(F+), 20(HF+), 28(CO+ or N2+), 32(O2+), 37(NH4F+), 44(CO2+), 120(Sn+), 136(SnO+) and 152(SnO2+). The majority of evolved gases from all FTO films were water vapor, carbon monoxide and carbon dioxide. Fluorine (m/z 19) was detected only in doped films and its intensity was very strong for highly-doped films at temperature above 400°C.

The annealing of phosphorus-ion-implanted cadmium telluride by a pulsed electron beam

Abstract: A pulsed electron beam of 10 µs FWHM has been successfully applied to anneal phosphorus-implanted CdTe. The sheet resistance drops to 6.3 × 102Ω/ from nearly infinite for the As-implanted wafers as the irradiation intensity exceeds 9.2 J/cm2. A p-type carrier concentration as high as 3 × 1018cm-3has been reached as measured by the van der Pauw and Hall techniques.

Nanoscale surface conductivity analysis of plasma sputtered carbon thin films

Abstract: Understanding of surface conductivity at the nanoscale is very important for surface activities e.g. bio-activity and electronic transportations. In this work, the co-relation of surface properties to surface conductivity has been investigated in carbon films prepared by plasma sputtering. A Field Emission Scanning Electron Microscopy (FE-SEM) study provided evidence of film growth in the form of the nano-domains (NDs). Conductive atomic force microscopy (C-AFM) was used to explore the influence of growth conditions on the local current flow in carbon thin films through the induced current variation across the NDs. It is found that the growth regime of the NDs has a close relation to the power density and the working pressure. The flow of current across the internal area of the ND surface is lower than the boundaries due to the difference of conjugation in sp2 hybridized carbon atoms. The mean current flow through the films as measured by C-AFM is in accordance with the resistivity of the films observed by the van der Pauw method.

Initial Stages of MOCVD Growth of Gallium Nitride Using a Multi-Step Growth Approach

Abstract: A multilayer buffer layer approach to GaN growth has been developed in which the thermal desorption and mass transport of low temperature buffer layer are minimized by deposition of successive layers at increased temperatures. High quality GaN with featureless surface morphology has been grown on (0001) sapphire substrate by metalorganic chemical vapor deposition using this multilayer buffer layer approach. The lateral growth and coalescence of truncated 3D islands (TTIs) nucleated on low temperature buffer layers at the initial stage of overlayer growth is affected by the thickness of the final buffer layer on which nucleation of TTIs takes place. The effect of the thickness of this buffer layer on the quality of GaN is studied by using scanning electron microscopy, van der Pauw geometry Hall measurements and cathodoluminescence and an optimum value of 400A is obtained.