Münster 1999 – scientific programme

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HL: Halbleiterphysik

HL 40: GaN III

HL 40.1: Talk

Friday, March 26, 1999, 09:30–09:45, H2

Characterization of free-carrier and crystal-structure properties of group III-nitride heterostructures by generalized infrared ellipsometry — •Mathias Schubert¹, Bernd Rheinländer¹, Craig M. Herzinger², Jürgen Off³, and Ferdinand Scholz³ — ¹Fakultät für Physik und Geowissenschaften, Halbleiterphysik, Universität Leipzig, Linnestraße 5, D-04103 Leipzig — ²Center for Microelectronic and Optical Materials Research, University Nebraska-Lincoln, NE 68588, U.S.A. — ³4. Physikalisches Institut, Kristallabor, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart

We report for the first time the application of infrared spectroscopic

ellipsometry (IR-SE) from 1 - 30 µm for non-destructive

characterization of free-carrier and crystal-structure properties of

group III-nitride heterostructures. This technique determines the

anisotropic infrared dielectric response within the reststrahlen range

of group III-nitride thin films regardless to the film thickness, or the

substrate material. Analysis of the dielectric functions of the

heterostructure components provides their characteristic lattice and

free-carrier influenced phonon properties. IR-SE can provide

sensitivity to thickness, phonon energies, free-carier concentration,

and vertical and horizontal mobilities for each layer within the

heterostructure. We propose the application of IR-SE for exploitation

of the phonon properties of group III-nitride alloys, and for

non-destructive control of free-carrier properties and alloy

compositions in heterostructures for possible device applications.