Critical thickness anisotropy in highly carbon-doped p-type (100)GaAs layers grown by metalorganic molecular beam epitaxy

The formation of misfit dislocations at the (100)GaAs substrate interfaces of thick highly carbon-doped p-type GaAs layers grown by metalorganic molecular beam epitaxy, was investigated using x-ray diffraction and transmission electron microscopy. The misfit dislocation lines were observed to be all aligned along one of the 〈011〉 directions on the substrate and were identified as being ‘β’ type. Enhanced migration of β dislocations in p-type GaAs coupled with heterogeneous dislocation loop formation at clusters of partially dissociated (CH3)3Ga molecules is proposed as a probable cause of the anisotropy.