Role of strain on the wavy growth onset in strain-balanced InGaAs-based multiquantum wells

Different strain-balanced InGaAs/InGaAs multiquantum wells (MQWs) were grown on (001) InP by changing the In composition in the wells and in the barriers in order to extend the absorption edge beyond 2 mu m for thermophotovoltaic applications. The increase of the elastic strain in the structures results in the formation of isolated highly defected regions having their origin from lateral layer thickness modulations. Experimental results are consistent with the existence of a critical elastic energy density for the development of MQW waviness. An empirical model to predict the maximum number of layers that can be grown without modulations as a function of the strain energy stored in the MQW period is presented.