The formation of self-assembled InAs and InAsxP1-x dots on InP has been studied, in particular with deposition conditions under which mainly coherent dots are developed. The samples were grown by metalorganic vapour phase epitaxy. Morphological investigations were performed by atomic force microscopy, with the instrument working in the contact mode as well as in the noncontact mode. Surface densities and height distributions were extracted, as a function of growth conditions. In addition, photoluminescence was used for investigations of the optical properties of capped InAs dots, formed under equivalent conditions. Comparisons between the two characterization techniques show a qualitative agreement with respect to the density of dots as well as their size homogeneity. It is also indicated that dots of binary InAs can be formed at deposition temperatures not higher than about 500[deg]C. Elevated deposition temperatures in this process result in an unintentional alloying mechanism due to exchange reactions at the interface, leading to the formation of ternary InAsxP1-x dots, which can be seen as a simultaneous increase in the energy of the light emission and the average dot size, indicating the widening of the energy gap in the quantum dots, which counteracts the decreased energy quantization in the larger dots formed at higher temperatures.

We have studied the influence of alloying induced chemical exchange reactions on the formation of self-assembled InAs dots prepared on InP and In0.52Al0.48As buffers lattice-matched to InP(001). Atomic force microscopy and low-temperature photoluminescence measurements have been used to characterize the dot properties. Strong differences in the islanding process are observed depending on the growth conditions and on the nature of the buffer layer. They are associated to variation in intermixing between the InAs deposit and the buffer layer.