Estudo da condutividade elétrica transversal de MoS2

Abstract

This Masters work studies the transversal electronical transport in thin films crystal structures of MoS2 for its chacacterization in nanometric scale, facilitating its application in nanotechnology. The Atomic Force Microscopy (AFM) technique is used, in special the Conductive mode (CAFM). MoS2 is a semiconductor with interesting properties that have been largely studied in the last years. The characterization we seek shall tell us about the bidimensional criytal’s electrical conductivity, transversal to its crystal plane, when varying the tip’s applied voltage and pressure. For this purpose the CAFM aplies a voltage difference between the tip of the microscope and the substract holding the sample, thus measuring the electrical current transversal to the Molibdenum Disulfide plane. Different electronical transport mechanisms can be the source of the currents measured by this technique. The measured current grows with the increment of the voltage and applied preassure. A DiodeResistor-Diode model is proposed to simulate the experiment and, with it, it's found that the resistence's value decreases with higher applied pressures. It is also found that the Schottky barrier in the semiconductor-metal tip interface has its potential height altered due to the variations in the applied pressure by the tip.