  We investigated the influence of deep levels on the electrical transport
properties of CdZnTeSe radiation detectors by comparing experimental data with
numerical simulations based on simultaneous solution of drift-diffusion and
Posisson equations, including the Shockley-Read-Hall model of the carrier
trapping. We determined the Schottky barrier height and the Fermi level
position from I-V measurements. We measured the time evolution of the electric
field and the electrical current after application of a voltage bias. We
observed that the electrical properties of CZTS are fundamentally governed by
two deep levels close to the mid-bandgap - one recombination and one hole trap.
We show that the hole trap indirectly increases the mobility-lifetime product
of electrons. We conclude that the structure of deep levels in CZTS are
favorable for high electrical charge transport.
