Design and implementation of a microcomputer-based instrument for hall effect measurements at room temperature

Date

3-2000

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Emmanuel A Florido

Abstract

A microcomputer-based instrument for hall effect measurements at room temperature was designed, implemented and evaluated. The instrument was used to investigate the electrical and transport properties of 1nN using the van der Pauw method. An electronic contact permutation circuit was implemented to aid switching of contacts. Also an electromagnet was designed and fabricated and was able to produce 2.1 kG at 3A with an air gap of 1 inch. Furthermore, an ADC card was designed and fabricated with 15uV resolution to measure hall voltages. A software interface was also developed using the Turbo C programming language. The data were stored in files specified by the user. The data was then plotted in Easy PlotTM software and linear fits were obtained. From the IV and 1VH plots obtained, the resistivity (7.80966 x 10-4 S3 cm), hall coefficient(4.44841 x 104 V cm/AT), conductivity (128046.259 ' cm-1), carrier concentration (1.40324 x 10 +21 cm-3) and mobility (5.69038056 cm2/Vs). Errors may be due to an unstable current source, inhomogeneous magnetic field and mainly because of the kind of sample used. The sample may have degraded through time and overexposed. It is recommended to have a constant and stable current source, homogeneous magnetic field, and new sample with good contacts must be used.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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