Relaxation mechanism of GaP/InGaAlP/GaAs heterostructure

Transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM) were carried out to investigate the structural properties of the GaP/In_0.48(Al_0.7Ga_0.3)_0.52P heterostructures grown on GaAs (0 0 1) substrates. The lattice-matched In_0.48(Al_0.7Ga_0.3)_0.52P/GaAs material system could be used as a defect-free substrate because no lattice misfit exists between the In(AlGa)P layer and the GaAs substrate. Both TEM and HREM measurements indicated that there were not only misfit dislocations, but also microtwins at the GaP/In(AlGa)P heterointerface. The mechanism of the microtwins formation is elucidated.