Pressure-induced structural transformations in Bi-doped amorphous germanium sulfide

The problem of $n$-type doping of amorphous germanium chalcogenides is tackled by applying a Bridgman anvil technique of high pressure. A study of Bi-doped ${\mathrm{Ge}}_{20}{\mathrm{S}}_{80-x}{\mathrm{Bi}}_x$ and ${\left({\mathrm{Ge}}_{42}{\mathrm{S}}_{58}\right)}_{100-x}{\mathrm{Bi}}_x$ has been made up to a pressure of 100 kbar for the first time. The appearance of two pressure-induced sharp structural transitions in ${\mathrm{Ge}}_{20}{\mathrm{S}}_{80-x}{\mathrm{Bi}}_x$ and one continuous transition in ${\left({\mathrm{Ge}}_{42}{\mathrm{S}}_{58}\right)}_{100-x}{\mathrm{Bi}}_x$ is observed. X-ray diffraction and differential thermal analysis of semiconductors (as prepared and pressure quenched) reveal the presence of two pressure-induced crystalline phases ${\mathrm{Bi}}_2$ ${\mathrm{S}}_3$ and Ge${\mathrm{S}}_2$. Such structural changes in the doped semiconductors may be the contributory factor in the $n$-type doping of the chalcogenide glass.