Direct tunnel ionization of deep impurities in the electric field of far-infrared radiation

Abstract

Ionization of semiconductor deep impurity centers has been observed in the far infrared where photon energies are several factors of ten smaller than the binding energy of the impurities. It is shown that the ionization is caused at high intensities by direct tunnel ionization in the electric field of the high power radiation. This optical method allows the investigation of the tunnelling process at electric bias fields well below the threshold of avalanche breakdown.