Characterization of deep impurities in semiconductors by terahertz tunneling ionization

Tunneling ionization in high frequency fields as well as in static fields i s suggested as a method for the characterization of deep impurities in semi conductors. It is shown that an analysis of the field and temperature depen dences of the ionization probability allows to obtain defect parameters lik e the charge of the impurity, tunneling times, the Huang-Rhys parameter, th e difference between optical and thermal binding energy, and the basic stru cture of the defect adiabatic potentials. Compared to static fields, high f requency electric fields in the terahertz-range offer various advantages, a s they can be applied contactlessly and homogeneously even to bulk samples using the intense radiation of a high power pulsed far-infrared laser. Furt hermore, impurity ionization with terahertz radiation can be detected as ph otoconductive signal with a very high sensitivity in a wide range of electr ic field strengths. (C) 2000 American Institute of Physics. [S0021-8979(00) 04508-4].