GaAs, GaAs:Si and GaAs:C films were deposited on GaAs substrates by Metal Organic Chemical Vapor Deposition( MOCVD) technique. The vibrational study of the heterostructures was performed by μ‐Raman technique, and measurements were made at different temperatures using a sample holder with a micro‐heater included within it. The spectral information was used to determine the strain caused in GaAs heterostructure because of the inclusion Si(a = 5.43095A) and C(a = 3.56683A) [1]. Raman spectra as a function of temperature show a shift towards lower energy values as temperature increases. The new normal modes of vibration that appears, and the corresponding shift is associated with the effort tensile in the lattice caused by the difference in thermal expansion coefficients between film and substrate [2], this tension has been bigger for the film doped with carbon.