We study the incorporation of indium into AlxGa1-xN/GaN quantum well (QW) structures with high indium concentrations above 25% for QW thicknesses in the range 2 nm clown to half a c-lattice constant under pulsed and continuous growth conditions. We want to clarify which processes limit the incorporation of indium and lead to a degrading layer structure. The data are discussed in the context of the adlayer proposed by theory (Northrup et al., 2000) [1]. The interplay of the adlayer with the incoming flux, the high desorption rate and segregation of indium can consistently explain the various observed phenomena. (C) 2014 Elsevier B.V. All rights reserved,