Microcomputer-based van der Pauw measurements for thin film characterization

Date

11-1997

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Demetrio A Yco, Jr.

Abstract

A microcomputer-based system for van der Pauw measurements was developed to characterize two III-V semiconductor thin films, namely: Indium Phosphide (InP) and Indium Antimonide (InSb). The implementation of the system included the design and construction of an analog interface module which houses an electronic permutation selector and a thermocouple amplifier circuit, assembly of the thin film characterization instrument developed by B.A.S. Ocfemia, installation and calibration of the PCADC12 card and the development of a software program to control hardware, gather data and compute for the resistivity, Hall coefficient, mobility and carrier concentration of the thin film sample for every rise in temperature in the range 150u-300u K. An updated van der Pauw method which utilizes the contact permutation averaging technique and the Newton-Raphson iterative approximation method was used for the resistivity and Hall measurements. The system was recalibrated for temperature monitoring and contact voltage measurements. Voltage-current characteristics investigations showed that the InP is no longer suitable for van der Pauw measurements since two of its contacts exhibited negative resistivity. The contacts may no longer be ohmic or may have degraded. Results of resistivity and Hall measurements on the InSb sample shows that the resistivity, Hall coefficient and carrier concentration of the sample is related exponentially to the temperature with coefficient of determinations ranging from 0.98 to 0.99. The mobility however showed that it has a linear relationship with temperature. Numeric data of the experiment are stored on data files which are protected under one directory created by the program.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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