Phonons and free-carrier properties of binary, ternary, and quaternary group-III nitride layers measured by infrared Spectroscopic Ellipsometry

A. Kasic, M. Schubert, J. Off, B. Kuhn, F. Scholz, S. Einfeldt, T. Böttcher, D. Hommel, D. J. As, U. Köhler, A. Dadgar, A. Krost, Y. Saito, Y. Nanishi, M. R. Correia, S. Pereira, V. Darakchieva, B. Monemar, H. Amano, I. AkasakiG. Wagner

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

This work reviews recent ellipsometric investigations of the infrared dielectric functions of binary, ternary, and quaternary group-III nitride films. Spectroscopic Ellipsometry in the mid-infrared range is employed for the first time to determine phonon and free-carrier properties of individual group-III nitride heterostructure components, including layers of some ten nanometer thickness. Assuming the effective carrier mass, the free-carrier concentration and mobility parameters can be quantified upon model analysis of the infrared dielectric function. In combination with Hall-effect measurements, the effective carrier masses for wurtzite n- and p-type GaN and n-type InN are obtained. The mode behavior of both the E1(TO) and A1(LO) phonons are determined for ternary compounds. For strain-sensitive phonon modes, the composition and strain dependences of the phonon frequencies are differentiated and quantified. Information on the crystal quality and compositional homogeneity of the films can be extracted from the phonon mode broadening parameters. A comprehensive IR dielectric function database of group-III nitride materials has been established and can be used for the analysis of complex thin-film heterostructures designed for optoelectronic device applications. Information on concentration and mobility of free carriers, thickness, alloy composition, average strain state, and crystal quality of individual sample constituents can be derived.

Original languageEnglish (US)
Pages (from-to)1750-1769
Number of pages20
JournalPhysica Status Solidi C: Conferences
Volume0
Issue number6 SPEC. ISS.
DOIs
StatePublished - 2003

ASJC Scopus subject areas

  • Condensed Matter Physics

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    Kasic, A., Schubert, M., Off, J., Kuhn, B., Scholz, F., Einfeldt, S., Böttcher, T., Hommel, D., As, D. J., Köhler, U., Dadgar, A., Krost, A., Saito, Y., Nanishi, Y., Correia, M. R., Pereira, S., Darakchieva, V., Monemar, B., Amano, H., ... Wagner, G. (2003). Phonons and free-carrier properties of binary, ternary, and quaternary group-III nitride layers measured by infrared Spectroscopic Ellipsometry. Physica Status Solidi C: Conferences, 0(6 SPEC. ISS.), 1750-1769. https://doi.org/10.1002/pssc.200303135