The fracture of single crystal gallium arsenide (GaAs) semi-conducting
wafers was studied. Prismatic beam specimens, cut at different crysta
llographic orientations from thin wafers, were loaded to failure in fo
ur-point bending. Fracture in these crystals occurred predominantly on
the {110} family of crystallographic planes. The critical normal and
shear stresses on the primary {110} failure planes of the specimens at
failure were calculated and a plane stress failure envelope was deter
mined. A model to predict the likelihood of failure at any stress stat
e was developed. Scanning electron microscopic analysis revealed that
failure in bending was initiated from surface defects that approximate
semi-elliptical cracks on the tension side.