Influence of high-index GaAs substrates on the 2D electron density of δ-doped pHEMT with an additional InxGa1-xAs (x > 0.15) thin layer embedded in the channelL. Bouzaïene, S. Rekaya, L. Sfaxi and H. MaarefEur. Phys. J. Appl. Phys., 29 3 (2005) 209-213DOI: https://doi.org/10.1051/epjap:2004219