Résumé
We have developed a model which describes the incorporation of aluminum in the solid phase of Ga1-xAlxM where M is As or N, taking into account the diffusion of the group In species through the gas phase in the vicinity of the substrate. In order to compare our model with experimental data, GaAlAs and GaAlN alloys were grown by low pressure (76 Torr) MOVPE. Art excellent agreement is obtained in the case of GaAlAs alloys, considering TEGa and TMA1 as diffusing species in a hydrogen ambient. For AlGaN alloys, we discuss here the nature of the species involved in the diffusion mechanism since the precursors pyrolysis occurs at lower temperature than the growth temperature. We thus use this model to discuss the nature of the diffusing species, which are clearly not TEGa and TMA1, but rather unstable species, like diethyl and monomethyl, resulting: from the thermal decomposition of the organometallics.