Influence of Substrate and Structure on Ag-Photodoping into Amorphous GeSe Films by Using a Holographic Method

Systematical changes in diffraction efficiencies through Ag-photodoping into amorphous GeSe thin films

“…1 shows the schematic diagrams for the holographic exposure and real-time diffraction efficiency (g) measuring systems and for interference effects in the chalcogenide film by two equal beams. A rectangular stage with a mirror and a sample holder was designed capable of precisely controlling the incident diffraction angle (0°< h < 80°) and sample rotation angle (0°< c < 180°), in which c rotation needs to fabricate two-dimensional photonic and quasi-photonic crystals using a multiple exposure holographic method [18,25].…”

“…Details of the a-Ge 25 Se 75 bulk preparation were described previously by Lee et al [3,18]. Ag and a-Ge 25 Se 75 thin films were successively thermally deposited on a p-type Si (1 0 0) substrate at a deposition rate of approximately 0.1-0.3 nm/s, under a vacuum of $2 Â 10 À6 Torr.…”

“…From a series of experimental results, we concluded that the substrate-dependence for Ag-photodoping could be explained by the diffusion of minority carriers in the films and the change of the magnitude and direction within the internal fields generated at the film interfaces [18]. In addition, we proposed that the magnitude of Ag-photodoping in the structure of the a-chalcogenide/ Ag/substrate depends strongly on the photodarkening-dominant process in the chalcogenide, related to the generation of valencealternation pairs (VAPs) [18,22,24]. The aim of the present work is to confirm that the Ag-photodoping effect into a-GeSe thin films exhibits a systematical change dependent on the film thickness and to explain the kinetics.…”

“…There are a number of reports explaining the kinetics of photodoping [9][10][11][12][13][14][15][16][17][18]. It is a well-known property that Ag atoms are more concentrated at the outer edges of the illuminated region than in the central region.…”

“…Until now, we have reported on the Ag-photodoping phenomena into chalcogenides in the following publications: the magnitudes of Ag-doping in the Ag/a-Sb 2 S 3 /Si and Ag/a-AsGeSeS/Si systems by illumination with a 325 nm HeCd laser and their wet-etching selectivities [12,22]; the possibility of Ag-photodoping into several crystalline chalcogenide compounds and their kinetics [23]; and the influence of substrate and structure on the Agphotodoping effect into a-GeSe thin films as 2 types of sample structures (Ag/a-SeGe/substrate and a-SeGe/Ag/substrate) [18]. From a series of experimental results, we concluded that the substrate-dependence for Ag-photodoping could be explained by the diffusion of minority carriers in the films and the change of the magnitude and direction within the internal fields generated at the film interfaces [18].…”