Scattering Mechanisms and Transport Properties of Semiconductors at Low Temperatures

Abstract

The purpose of this project is to verify scattering mechanisms in semiconductors by measuring transport properties and producing data that reflects existing research. The Hall effect is utilized to measure the resistivity, mobility and charge carrier concentration of the semiconductors: indium tin oxide (ITO), p-type silicon, and n-type silicon. By verifying and improving the measurement procedure, newer semiconductors can be produced and studied for desirable characteristics which are applicable throughout modern technology. Using liquid nitrogen to acquire the temperature dependent properties of the ITO and silicon samples, scattering mechanisms and trends related to the dopant concentration were measured. The temperature dependent electrical characteristics of three silicon samples doped with antimony, arsenic, and boron, produced carrier densities and mobilities that were consistent with existing research. At low temperatures, the samplesโ€™ mobilities were impacted by impurity scattering and at higher temperatures the mobilities were impacted by phonon scattering, as seen in both the data and previous research. The carrier concentration of ITO was measured over a broad range of temperatures to be 1.0*1021 cm-3, which is large for a semiconductor causing the material to behave like a weak metal. By producing measurements consistent with theory, similar methodology can be applied to wide band-gap semiconductors which have been less researched in the past, specifically TiO2 which is currently being produced by the Tate lab at Oregon State University

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