  The geometry of electrodes is one of the most important factors in
determining the performance of orthogonal-strip detectors. The aim of this work
is to study the performance of a 5 mm thick cross-strip CdZnTe detector with
different electrode widths. Our study consists of two main parts, simulations
and experiments. We utilized four different anode sizes ranging from 0.1 mm to
0.6 mm. The anodes were interspersed with steering electrodes with varying
sizes from 0.3 mm to 0.85 mm. The maximum gap size between the anodes and
steering electrode strips was set to 0.3 mm, while the minimum gap size was
0.125 mm. The performance of the detector was investigated in terms of the
steering electrode bias voltage, the energy resolution, and the charge sharing
effect. For simulations, we developed a C++ based simulation program for charge
transport inside the CdZnTe detector and charge collection at the electrodes.
For photon interactions we used GEANT4 toolkit and for electric field and
weighting potential simulations we used COMSOL software. The results
demonstrated that -50 V is the optimal steering electrode bias for our detector
when -500 V was applied to the cathodes and that the energy resolution
performance drops with increasing steering electrode width. Also, the charge
sharing effect becomes more dominant for larger steering electrode sizes. The
experimental result are further compared with the simulations. The results are
in a good agreement and the comparison validates our simulation model.
Although, our simulation framework has need of better estimation for the
intrinsic noise of CdZnTe. These results suggest that an optimization study
between electrode widths and steering electrode bias is required to obtain the
best performance in orthogonal-strip CdZnTe detectors.
