Charge Collection Efficiency in Segmented Semiconductor Detector Interstrip Region

Charged particle semiconductor detectors have been used in Ion Beam Analysis (IBA) for over four decades without great changes in either design or fabrication. However one area where improvement is desirable would be to increase the detector solid angle so as to improve spectrum statistics for a given incident beam fluence. This would allow use of very low fluences opening the way for example to increased time resolution in real-time RBS or analysis of materials that are highly sensitive to beam damage. In order to achieve this goal without incurring the costs of degraded resolution due to kinematic broadening or large detector capacitance, a single-chip segmented detector (SEGDET) was designed and built within the SPIRIT EU infrastructure project. In this work we present the Charge Collection Efficiency (CCE) in the vicinity between two adjacent segments focusing on the interstrip zone. Microbeam Ion Beam Induced Charge (IBIC) was used to perform X-Y mapping of CCE with different ion masses and energies, as a function of detector operating conditions (bias voltage changes, detector housing possibilities and guard ring configuration). We show the CCE in the active area edge region and have also mapped the charge from the interstrip region, shared between adjacent segments. The results indicate that the electrical extent of the interstrip region is very close to the physical extent of the interstrip and guard ring structure with interstrip impacts contributing less than 8% to the complete spectrum. The interstrip contributions to the spectra can be substantially reduced by an offline anticoincidence criterion through the list mode data analysis, which should also be easy to implement directly in the data acquisition software.