Optical properties and damage analysis of GaAs single crystals partly amorphized by ion implantation

• Published in: Journal of applied physics 1984-11, Vol.56 (10), p.2664-2671
• Main Authors: ERMAN, M, THEETEN, J. B, CHAMBON, P, KELSO, S. M, ASPNES, D. E
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Visible and ultraviolet spectra
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.333785

Dielectric functions of partly amorphized GaAs layers produced by deep ion implantation of different doses of 270-keV As+ ions in crystalline (c-) GaAs have been measured from 1.5 to 6.0 eV by spectroscopic ellipsometry. We show that these dielectric functions cannot be described as physical mixtures of amorphous (a-) and c-GaAs, as such models exhibit strong deviations with respect to the data near 3 eV. We determine representations of these dielectric functions as finite sums of harmonic oscillators, which allows us to describe these spectra as analytic functions of a single parameter related to the amount of damage. In this harmonic oscillator approximation (HOA), we show that damage profiles of ion-implanted material can be nondestructively determined from ellipsometric spectra in terms of multilayer models. In a representative case, good agreement is found between damage profiles determined nondestructively in the HOA and destructively by chemical etching.