Effects of high-temperature annealing on the optical absorption of Ca:YIG films

Abstract

Effects of high-temperature annealing on structural and optical properties of highly ordered porous alumina membranes Appl. Phys. Lett. 85, 4364 (2004); 10.1063/1.1815072Effect of high-temperature annealing on electrical and optical properties of undoped semi-insulating GaAsThe effect of high-temperature annealing on the optical properties of a calcium doped yttrium iron garnet ͑Ca:YIG͒ film were studied. The optical absorption was examined for a film of Ca 0.18 :YIG reduced in an atmosphere of N 2 at temperatures above 900°C. During the annealing, the optical absorption initially decreased below the as-grown value as expected, but subsequently increased to a value greater than that for the as-grown film as the annealing temperatures were increased. The changes observed in the optical absorption are believed to be due to the introduction of oxygen vacancies in the film as a result of the annealing. Initially, the added oxygen vacancies simply compensate the Ca 2ϩ , while successive annealings introduce excess vacancies which lead to a new absorption mechanism. The results of this study and the expected mechanism for the effect are reported.