Influence of Guard Ring Electrode on Performance of (CdZn)Te Pixel Detector Characterized by Laser-Induced Transient Current Technique
Abstrakt
In our presentation we introduce investigation of guard ring influence on performance of commercially available Redlen (CdZn)Te 8x8 pixel detector. By means of laser induced transient current technique it was shown that guard electrode acts by the same way as non-collecting grid in coplanar detectors when guarded pixel is illuminated by the laser diode.
This phenomenon is also observed when we apply interelectrode voltage between the guard ring and the pixel. Moreover, in this particular case the interelectrode voltage polarity has a weak impact on electrodes behavior.
Therefore, the guard ring not only reduces the dark current, but also improves the charge carriers transient time and the charge collection efficiency. Illumination of the other spots (guard ring, spots between guard and pixel, another pixel outside the ring) and simultaneous measurement of signals on both electrodes allowed us to investigate the charge sharing effects.
By varying positive interelectrode voltage applied to the guard ring we also managed to control charge collection on pixel. Measured data showed that the pixel can be effectively shielded from charge carrier clouds generated under the pixels outside of the guard ring.