The HVPE epitaxy technique involves chloride molecules as growth precursors which nucleate on monocristalline semiconductor surfaces rather than on dielectric Si-related surfaces. HVPE appears then as the preferential tool for achieving selective epitaxy applications as total freedom is left for the design of the masks. The HVPE growth is a near equilibrium growth method which is mainly limited by the kinetics of surface processes, that is by the growth anisotropy as a function of the exposed (growing) surfaces of the crystal. HVPE is thus supposed, if mastered, to be a powerful tool for the control of crystal morphologies.
LASMEA has been successful in stabilising reproducible morphological profiles (beam-like shape, pyramid-like shape) on sub-micrometer or micrometer scales by selective growth on GaAs (001), (110) and {111} substrates as a function of experimental parameters (growth temperature, composition of the vapour phase) of which influence was clearly determined and modelled.
Applications involve the fabrication of new structures with controlled morphologies such as alternate periodic layers for non linear optics applications, mesa networks for Photonic Bandgap applications, quantum wire arrays on top of morphologically controlled mesas.