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 lO18 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 density of microdefects has been established by TEM: perfect or faulted interstitial type dislocation loops lying in the (11O] 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.