Threading dislocations in InxGa1-xAs/GaAs heterostructures

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 <211≳ and <110≳, and [001] directions, respect...