Infrared spectroscopic ellipsometry for nondestructive characterization of free-carrier and crystal-structure properties of group-III-nitride semiconductor device heterostructures

Mathias Schubert, Alexander Kasic, Stephan Figge, Marc Diesselberg, Sven Einfeldt, Detlef Hommel, Ulrich Köhler, Donat Josef As, Jürgen Off, Bertram Kuhn, Ferdinand Scholz, John A. Woollam, Craig M. Herzinger

Research output: Contribution to journalArticle

4 Scopus citations


Infrared Spectroscopic Ellipsometry is presented as a feasible and novel technique for contactless and nondestructive measurement of free-carrier and crystal-structure properties in the characterization of complex semiconductor heterostructures for device applications. Infrared-active lattice modes and coupling of free-carrier plasmons to longitudinal-optical lattice phonon modes strongly affect the infrared-optical response of semiconductor materials. Analysis of ellipsometry data from 2 μm to 100 μm can provide precise information on phonon mode frequencies and broadening parameters, static dielectric constants, free-carrier concentration, and free-carrier mobility at optical frequencies of III-V compound semiconductors, even for films with thicknesses only a fraction of the probing wavelengths. Alloy composition, strain, crystal quality, and free-carrier properties of constituent layers in thin-film structures, designed for optoelectronic or electronic device applications, can be derived. We demonstrate the characterization of coherent and incoherent light emitter structures based on group-III-nitride materials, where information such as concentration and mobility of free carriers in n- and p-type regions, thickness, composition, and quality of device constituents are accessible.

Original languageEnglish (US)
Pages (from-to)58-68
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - Jan 1 2001



  • AlGaN
  • AlInN
  • Anisotropy
  • Dielectric function
  • Ellipsometry
  • Free-carrier absorption
  • GaN
  • InGaN
  • Infrared
  • Laser diode
  • Light emitting diode
  • Phonon modes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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