The analytical, structural and electrophysical techniques have been applied to studies of the thermal degradation mechanism appearing in diode structures with the Schottky barrier Au-Mo-TiBxGaAs. It was shown that the rapid thermal annealing at T = 600 °C during 60 sec in hydrogen atmosphere results in creating the ELS type center in the space charge region of GaAs. This center is represented by the complex VGa+VAs, which has been confirmed by photoluminescence measurements. It causes the appearance of excess current at the initial part of current-voltage characteristic.