STUDY ON STACKING-FAULTS AND MICROTWINS IN WIDE BANDGAP II-VI SEMICONDUCTOR HETEROSTRUCTURES GROWN ON GAAS

ZnMgSSe and ZnSSe layers grown on GaAs substrates with GaAs buffer lay ers by molecular beam epitaxy have been examined by transmission elect ron microscopy(TEM). The depth level at which paired triangular stacki ng faults are nucleated in the ZnMgSSe/GaAs heterostructure has been i nvestigated by using the plan-view TEM technique. It has been found th at in the ZnMgSSe/GaAs heterostructure the nucleation of the paired st acking faults occurs within a range of depth which starts at the II-VI /GaAs interface and ends at a level that is above the interface by abo ut 120 nm. The dominant type of defects in ZnSSe layers, which have th e single triangular shape, has been identified to be microtwins by hig h resolution TEM.