Comparative study of microdefects in dislocation-free, heavily Si doped VB GaAs by DSL etching, NIR phase contrast microscopy, TEM and X-ray diffuse scattering

Microdefects in as-grown and annealed VB GaAs (Si > 5 x 1018 cm−3) have been studied by four methods. The nature and density of microdefects has been established by TEM: perfect or faulted interstitial type dislocation loops lying in the 110 and 111 planes have been found. Direct comparison between the results of TEM study and other methods has been performed. Photo-etching reveals microdefects in the form of microroughness. Large loops (micrometer size) in as-grown and annealed material could be clearly discerned by this method. NIR phase contrast microscopy is effective in analysing the loops which are enlarged during high temperature annealing. Diffuse X-ray scattering is suitable for qualitative assessment of the density and type of microdefects. From etching experiments a speculative argument has been obtained on the involvement of Si in the formation of interstitial type faulted loops.