Phonons and free carriers in strained hexagonal GaN/AlGaN superlattices measured by infrared ellipsometry and Raman spectroscopy

M. Schubert, A. Kasic, J. Šik, S. Einfeldt, D. Hommel, V. Härle, J. Off, F. Scholz

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Phonon and free-carrier effects in strained hexagonal (α) {GaN}l-{AlxGa1-xN}m superlattice (SL) heterostructures are studied by infrared spectroscopic ellipsometry (IRSE) and micro (μ)-Raman scattering. Growth of the heterostructures was performed by metal-organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy on (0001) sapphire. Unstrained 0.5-1 μm-thick α-GaN layers were deposited prior to the SLs. SL phonon modes are identified combining results from both IRSE and μ-Raman techniques. The average compressive SL stress can be estimated from the shift of the GaN-sublayer phonon modes. The IRSE data are sensitive to free carriers within the GaN sublayers. For the MOVPE grown SL structures, the free-carrier mobility is anisotropic which indicates vertical carrier confinement.

Original languageEnglish (US)
Pages (from-to)178-181
Number of pages4
JournalMaterials Science and Engineering B: Solid-State Materials for Advanced Technology
Volume82
Issue number1-3
DOIs
StatePublished - May 22 2001

Keywords

  • AlGaN
  • Ellipsometry
  • Infrared
  • Optical properties
  • Strain
  • Superlattice phonons

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Fingerprint Dive into the research topics of 'Phonons and free carriers in strained hexagonal GaN/AlGaN superlattices measured by infrared ellipsometry and Raman spectroscopy'. Together they form a unique fingerprint.

  • Cite this