Composition dependence of physical and optical properties in Ge-As-S chalcogenide glasses.

The composition dependence of density ( d ), refractive index ( n ) and optical bandgap ( E g ) of Ge-As-S chalcogenide glasses is investigated. It is shown that d correlates linearly with sulfur content but relatively poorly with the mean coordination number (MCN). It is also shown that n does not correlate directly with d , and instead a semi-empirical relation based on the molar refractivity ( R ) of Ge, As and S is derived, permitting to predict n from d with < 1% error. A convenient method based on diffuse reflectance is proposed to measure E g of Ge-As-S glasses with good accuracy. It is shown that the value of E g is dominated by the S content. These findings make it convenient to tailor the physical and optical properties of glasses in Ge-As-S system. [ABSTRACT FROM AUTHOR]