Résumé
We present magneto-transport measurements performed on three AlGaN/AlN/GaN heterostructures up to 14 T for various temperatures in the range 4-300 K. The obtained longitudinal and Hall conductivities are processed by mobility spectrum algorithms in order to extract the number and type of carriers in the samples. A single carrier is found in the whole structure in agreement with the first subband occupancy of the triangular quantum well which forms at the AlN/GaN interface. The temperature dependences of the density and mobility of the two dimensional electron gas are plotted for all three samples and compared with respect to their layer structures.