ACOUSTOELECTRIC SPECTROSCOPY OF GAAS SURF ACE

Surface levels in a heterostructure i - GaAs - epilayer GaAs are inves tigated using transverse acoustoelectric voltage in the layered system LiNbO3-GaAs (single crystal GaAs with epilayer GaAs). The effective c ross-section on electron trapping centres S(n) approximately 10(-15) c m2 and energetic level of surface states E(te) approximately 0.47 eV ( optical measurements ), and 0.42 eV ( thermal measurements ) are deter mined. These parameters correspond to the centre EL2, which is the int rinsic defect of the crystal structure at the crystal base - epilayer interface.