LINEAR-X-RAY DETECTOR ARRAY MADE ON BULK CDZNTE FOR 30-SIMILAR-TO-100KEV ENERGY

A CdZnTe detector grown by the high pressure Bridgman (HPB) growth tec hnique was tested using high energy x-rays (30 similar to 100 keV), an d the performance was compared with a commercially available NaI scint illating detector of 5 cm thickness. The charge collection efficiency of a CdZnTe detector is as high as 90% at relatively low electric fiel d, 600 V/cm. At high x-ray photon energies, the detection efficiency i s reduced due to the thickness of the CdZnTe. A 32 channel linear arra y was fabricated on 1.2 similar to 1.7 mm thick CdZnTe, of which the d etector area was 175 x 800 mu m(2) and the pitch size 250 mu m. The me asured dark current for the 16 element detector was as low as 0.1 pA a t 800 V/cm with an excellent uniformity. Energy spectra were measured using a Co-57 radiation source. A small pixel effect and charge sharin g were observed. The energy resolution was improved and compared with the large area detector. The array detector gave an average 5.8% full- width-half-maximum (FWHM) at 122 keV photopeak. The large area detecto r of the same material before fabrication exhibited a low energy tail at the photopeak, which limits the photopeak FWHM to 8%.