Threading dislocations in InxGa1−xAs/GaAs heterostructures

Publisher Website
Google Scholar
Abstract
Threading dislocation morphologies and characteristics, as well as their generation conditions in InxGa1−xAs films grown by molecular beam epitaxy on GaAs (001) substrates have been investigated, mainly using cross‐sectional transmission electron microscopy. The 3‐μm‐thick InxGa1−xAs films are mostly examined for x ranging over x=0.01, 0.05, 0.1, 0.15, 0.2, 0.3, and 0.5. Moreover, for x=0.2, epitaxial layers having film thicknesses of 0.5, 1, and 2 μm are investigated. The formation of a high density of threading dislocations which reach the film surface is detected in epilayers of x≥0.2 at a fixed film thickness of 3 μm and with film thicknesses greater than 2 μm at x=0.2. In layers of x≤0.15, such threading dislocations are rarely detected, although dislocation segments on the {111} planes threading into the upper regions from the interface are frequently observed. Most of the observed threading dislocations are 60° and pure‐edge type dislocations along the x≤0.15; the latter predominantly exist in layers of x≥0.3. In epilayers of x=0.2, the two types of threading dislocations mentioned above coexist. It is also discussed that the formation of the above‐mentioned threading dislocations is strongly associated with misfit dislocations which are introduced in the InxGa1−xAs layers under the different growth modes, depending on x.