Technological aspects of development of pixel and strip detectors based onCdTe and CdZnTe

Current and spectrometrical characteristics, stability in time and reliabil ity of pixel and strip detectors depend on initial material properties, cry stal processing quality and contacts manufacture technology. The work prese nts analysis of current-voltage and spectrometrical characteristics for ini tial CdTe and CdZnTe crystals applied for pixel and strip detectors manufac ture. The crystal surface preparation before contacts manufacture comprises a modified technology. The contacts were made by photolithography with the surface protected by photoresist with further windows lift-off and crystal surface metallization in lifted-off windows. Metal pads were made by gold deposition from chloroauric acid. Thermocompression, ultrasonic and purse w irebonding, as well as traditional contacts glueing method for CdTe and CdZ nTe detectors have been tested for contacts wiring. The pulse wirebonding h as revealed the best results. Wiring is made of gold wire with a diameter o f 30 mum and is good enough for pixel and strip wirebonding, providing rath er low labour-intensiveness for their assembly by standard equipment. The p ossibility of fabrication of pressing contacts to strip and pixel detectors by Zebra elastomeric connectors has been investigated. The pressing contac ts have provided qualitative and reliable electrical contact and signal lay out from pixels and strips to readout electronics. Developed technologies w ere applied in the manufacture of the following CdTe and CdZnTe detectors: 4 x 4 pixels detector with rectangular pixels 0.65 x 0.65 mm and pitch 0.75 mm; 4 x 4 pixels ring multiple-electrode detector with anode diameter 0.32 mm and pitch 0.75 mm; strip detector with 100 mum width strip and 125 mum pitch. The 4 x 4 pixels CdZnTe detector has provided at optimal temperature energy resolutions of 808 eV and 1.19 keV at energies of 5.9 and 59.6 keV, respectively. Interstrip resistance between two strips with a distance of 25 mum on detector was 2-8 G Omega. (C) 2001 Elsevier Science B.V. All righ ts reserved.