Abstract: Disclosed is a process for fabricating mixed crystals and, in particular, III-V semiconductors, in which at least one component of the composition of the mixed crystal is transferred in a reactor from a source into a vapor phase containing hydrogen and chloride compounds as well as a carrier gas and mixed with said component or other components of said composition of said mixed crystal, transported to a substrate and precipitated on said substrate. The invented process is distinguished in that in order to vary the growth rate between approximately 1 <m/h and approximately 500 <m/h, the overall pressure is varied between approximately 80 mbar and approximately 1 mbar.