Optical and electrical properties of Ag-As-S glasses

Abstract

Physical properties of Ag2S-As2S3 glassy alloys have been studied as a function of the Ag atomic concentration x. With an increase in x, the optical-absorption edge exhibits a red shift, while the steepness of the Urbach tail changes little. In the glasses with x≥15, the electrical conductivity is governed by Ag+ ionic conduction. The ionic conductivity exponentially increases with x, and in contrast the hole conductivity hardly changes with x; however, the activation energies for the ionic and the hole conductivity are nearly the same at about 0.4 eV for compositions with 15 ≤x≤35. These observations are discussed on the basis of atomic and electronic structures in Ag2S-As2S3 glasses.

Photoinduced surface deformations in ion-conducting Ag–As–S glasses. II. Anisotropic deformation produced by large light spots

“…Second, it has been demonstrated that 2.6 eV light does not produce the pattern. This is because the absorption coefficient for 2.6 eV light in the Ag-As-S film is 10 5 cm Ϫ1 , 8 so that the guided mode cannot practically propagate. Third, the ͑anti͒crater deformations can be prominent only in the direction perpendicular to the electric field of light, since the propagation of guided waves follows the Mie scattering process.…”

Photoinduced surface deformations in ion-conducting Ag–As–S glasses. I. Isotropic deformations produced by small light spots

“…%, which were employed in the previous compositional study. 10 The glass ingots were polished to disks with a thickness of ϳ0.2 mm, and then, were annealed at the glass transition temperatures for stabilization.…”

“…On the other hand, the optical band gap energy decreases with an increase in the Ag content, and in AgAsS 2 it is reported to be 2.1 eV. 10 Accordingly, when such a glass is exposed to light, electrons and holes may be photoexcited, and only holes can diffuse away, which gives rise to a Dember voltage, i.e., the illuminated region being negatively charged. In response, Ag ϩ ions in unilluminated regions will migrate toward the illuminated region.…”

“…In short, the glass can be regarded as an ion-conducting amorphous semiconductor. 7 For instance, in AgAsS 2 glass at room temperature, the electrical conductivity of 10 Ϫ5 /⍀ cm is governed by Ag ϩ ions, [8][9][10] and the electronic component of 10 Ϫ8 /⍀ cm is provided by holes. 10 No evidence suggesting electron motions has been obtained.…”

“…7 For instance, in AgAsS 2 glass at room temperature, the electrical conductivity of 10 Ϫ5 /⍀ cm is governed by Ag ϩ ions, [8][9][10] and the electronic component of 10 Ϫ8 /⍀ cm is provided by holes. 10 No evidence suggesting electron motions has been obtained. On the other hand, the optical band gap energy decreases with an increase in the Ag content, and in AgAsS 2 it is reported to be 2.1 eV.…”