Structural studies of compounds in the series GaS_xSe_1−x (0⩽x⩽1) grown by iodine vapour transport

Abstract

A discontinuity in the length of thec-axis of compounds in the series GaS _x Se_1−x ) is observed at the compositionx=0.25. This is thought to be caused by a transition from theβ structure of GaS to theε structure of GaSe. Although lattice parameter measurements indicate that the transition is abrupt, structure factor calculations and observations of the form of the (0 0 0 1) surface growth features indicate that the transition is not sharp, but takes place over the composition range 0.2⩽x⩽0.3. Growth features change in form asx varies, from hexagonal spirals characteristic of GaS to triangular spirals typical of GaSe.