Ultraviolet optical absorptions of semiconducting copper phosphate glasses

摘要

Ultraviolet optical absorptions of semiconducting copper phosphate glasses with batch compositions of 40percnt;, 50percnt;, and 55percnt; CuO have been examined as a function of lsqb;Cu2+rsqb;/lsqb;Cutotalrsqb; in the glasses. The optical energy gap,Eopt, obtained from the fundamental absorption edge depends upon both glass composition and the ratio lsqb;Cu2+rsqb;/lsqb;Cutotalrsqb; in the glass.Eoptincreases as CuO content and lsqb;Cu2+rsqb;/lsqb;Cutotalrsqb; in the glass are raised. This trend is explained by speculating upon the energy band structure of copper phosphate glass. However, the Urbach energy, Dgr;E, obtained from the tail of the optical absorption edge is affected solely by lsqb;Cu2+rsqb;/lsqb;Cutotalrsqb; in the glass. An absorption band of Cu1+(in its crystal field) occurs in the vicinity of the absorption tail and is responsible for the increase of Dgr;Ewith reducing lsqb;Cu2+rsqb;/lsqb;Cutotalrsqb; in the glass.