Defect studies in ZnSSe and ZnMgSSe by chemical etching and transmission electron microscopy

ZnSSe and ZnMgSSe epitaxial layers grown on (001)GaAs substrates are characterized by etching and transmission electron microscopy (TEM). It is found that etch pits etched by bromine-methanol correspond to stacking faults in ZnSSe. Tbese stacking faults, whose Burgers vector is 1/3 [111], are extrinsic. It is found that stacking faults lying on (1 (1) over bar 1) and ((1) over bar 11) cannot be revealed by this etchant in ZnSSe. TEM establishes that etch pits in ZnMgSSe etched by HCl correspond not only to stacking faults but also to threading dislocations. Furthermore, all stacking faults lying on the four equivalent (111) planes can be observed as etch pits in ZnMgSSe.