Photosensitivity of germanium oxide and germanosilicate glass sol-gel films

Germanium oxide and germanosilicate glass films were fabricated using a sol -gel spin coating method. The formation and photobleaching of the optical a bsorption band of the films in the 5-eV region were measured as a function of annealing under a reducing atmosphere and ultraviolet (UV) illumination. A greater amplitude in the 5-eV absorption band was observed with increasi ng annealing time due to the formation of more germanium-related oxygen vac ancies in the films. Also, the photobleaching of the absorption band increa sed with increasing illumination time. Although the amplitude of the absorp tion band in 50GeO(2)-50SiO(2) glass films is greater than that in germaniu m oxide glass films because of higher annealing temperature, germanium oxid e glass films are more photosensitive due to the greater photobleachable ne utral oxygen monovacancy (NOMV) concentration than non-photobleachable neut ral oxygen divacancy (NODV) concentration in the films. (C) 1999 Elsevier S cience B.V. All rights reserved.