Optoelectronic and structural properties of Er-doped sputter-deposited gallium-arsenic-nitrogen films

Erbium-doped gallium-arsenic-nitrogen thin films were prepared by cosputter ing a crystalline GaAs target partially covered with small pieces of metall ic erbium in an Ar+N-2 atmosphere. The films were deposited near room tempe rature and under increasing partial pressures of nitrogen P(N-2). The inves tigation of the films included ion beam analysis, optical spectroscopy in t he infrared-visible-ultraviolet energy ranges, Raman scattering, and photol uminescence measurements. According to the experimental results, all films present an amorphous structure and nitrogen contents that scale with P(N-2) . Increasing amounts of nitrogen induce the widening of the optical band ga p and a systematic redshift of the Raman signal of the films considered. Th e intensity of the Er-related light emission at similar to0.8 eV also incre ases at higher nitrogen contents. A detailed study of the absorption bands in the infrared region allowed the identification of different vibration mo des involving gallium, arsenic, and nitrogen atoms. The combined analysis o f the compositional data and of the infrared absorption bands provided a co nstant of proportionality between the nitrogen content in the films and the integrated absorption due to Ga-N bonds. Where applicable, comparisons bet ween the optoelectronic and structural characteristics of amorphous and cry stalline gallium-arsenic-nitrogen compounds were made. (C) 2001 American In stitute of Physics.