Space charge oscillations in semiinsulating CdZnTe

Our work focuses on a detailed analysis of non-trivial temporal evolution of the electric field measured by the Pockels effect in a CdZnTe planar sample after biasing. The electric field varies, and in a couple of seconds, it reaches a steady state. We have observed an undershoot of the electric field evolution close to the cathode which is a sign of a local oscillation of the space charge density. An advanced deep level analysis based on thermal emission results in a single hole trap with energy Ev + 0.87 eV responsible for complex electric field behavior. Moreover, we simulated an influence of a deep level concentration Nt on the local electric field oscillations: with a higher Nt the undershoots turn to the oscillations, while with a lower Nt, the undershoots turn to the monotonous temporal evolution of the electric field.