High E-field microwave properties of bulk amorphous semiconductors

The effects of high microwave electric fields on bulk amorphous semiconductors were studied at room temperature. Samples of eight different glasses were mounted in the center of a reduced height, X-band waveguide in a sandwich geometry parallel to the electric field of the dominant mode. Samples were 90 mil (2.286 mm) square by 8.5 mil (0.2159 mm) thick with thin-film CrAu electrodes. The microwave conductivity remained constant at field strengths below a critical value near 10⁴V/cm. Above this value, which depends upon the microwave pulse length, switching to a low-resistance state was observed with the thermal breakdown as the switching initiation mechanism.