Multiphonon trap ionization mechanism in amorphous SiN_x

The charge transport mechanism in amorphous silicon nitride (a-SiN_x) is experimentally analyzed in a wide range of electric fields and temperatures. The Frenkel effect with thermally assisted tunneling (TAT) and the multiphonon mechanism were used to describe the trap ionization. It is shown that the widespread Frenkel effect with TAT formally describes the experiment, but the agreement with the experiment is obtained if a small frequency factor (10⁹ s⁻¹) and a large tunneling effective mass (m*=3m₀) are used. Thus, the Frenkel effect does not describe the charge transport in a-SiN_x. The charge transport in a-SiN_x is satisfactorily described by the multiphonon trap ionization mechanism with the following parameters: m* = 0.6m₀, thermal and optical energies - W_T = 1.6 eV and W_OPT = 3.2 eV, respectively.