Infrared Reflectivity Spectroscopy of Short Period AlGaN/GaN Superlattice Optical Phonons

Master's Thesis
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Abstract

Extensive studies of GaN and AlN compounds led to several microelectronic and optoelectronic applications for these bulk materials. Nonetheless, many characteristics of AlGaN/GaN superlattices are not well known. In particular, scientists have not determined all the properties of phonons in these materials. In order to more fully understand phonon characteristics, this study reports infrared (IR) reflectivity measurements of AlGaN/GaN short period superlattices. Reflectivity measurements of each sample were taken using a Fourier Transform IR vacuum spectrometer. Additionally, a method for measuring low temperature IR spectrum was developed along with a program to analyze spectra. Comparing the experimental spectra with theoretical calculations determined the longitudinal and transverse optical phonon energies present in the AlGaN/GaN superlattices. Through the examination of different AlGaN/GaN superlattice combinations, characterization of phonon energies versus material composition were obtained. Furthermore, new phonons, not present in bulk AlN and GaN, were discovered. Phonon characteristics were additionally measured as a function of temperature, confirming the expectation that phonon energies decrease with increasing temperature.

Attributes

Attribute NameValues
URN
  • etd-04172008-172331

Author Joseph B Herzog
Advisor James L. Merz
Contributor Debdeep Jena, Committee Member
Contributor Alexander Mintairov, Committee Member
Contributor James L. Merz, Committee Chair
Degree Level Master's Thesis
Degree Discipline Electrical Engineering
Degree Name MSEE
Defense Date
  • 2008-04-03

Submission Date 2008-04-17
Country
  • United States of America

Subject
  • spectroscopy

  • GaN

  • phonons

  • superlattice

  • infrared

  • reflectivity

  • AlGaN

  • optical

Publisher
  • University of Notre Dame

Language
  • English

Record Visibility and Access Public
Content License
  • All rights reserved

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