Formation and structure of inverted hexagonal pyramid defects in multiple quantum wells InGaN/GaN

We have determined the structure of inverted hexagonal pyramid defects (IHPs) in multiple quantum wells InGaN/GaN by high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM). HAADF STEM images reveal definitely that the IHP nucleates at a threading dislocation and grows in the form of a thin six-walled structure with InGaN/GaN {101̄1} layers. It has been found that IHPs start even at In-rich dots under adverse growth conditions.