The two layer system AlyGa1-yAs on GaAs is studied in the range (0≤y>~1). The open photoacoustic cell technique is used to obtain thermal diffusivity, thermal conductivity, heat capacity, and the thermal expansion coefficient. It is shown that the thermal properties of the individual layers can be determined using the low modulation frequency regime models without actually separating the two layer system. The possibilities and advantages of the approach for the thermal characterization of layered semiconductor systems are discussed. © 2000 American Institute of Physics.