High-resolution CdTe detector and applications to imaging devices

• Published in: IEEE transactions on nuclear science Vol. 48; no. 3; pp. 287 - 291
• Main Authors: Takahashi, T., Watanabe, S., Kouda, M., Sato, G., Okada, Y., Kubo, S., Kuroda, Y., Onishi, M., Ohno, R.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2001; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bias; Cadmium compounds; Cadmium telluride; Cadmium tellurides; Detectors; Devices; Diodes; Electric potential; Energy resolution; High-resolution imaging; Leak detection; Leakage current; Pixels; Prototypes; Pulse measurements; Schottky diodes; Voltage
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/23.940067

Using a high quality Cadmium Telluride (CdTe) wafer, we formed a Schottky junction and operated the detector as a diode (CdTe diode). The low leakage current of the CdTe diode allows us to apply a much higher bias voltage than was possible with the previous CdTe detectors. For a relatively thin detector of /spl sim/0.5 mm thick, the high bias voltage results in a high electric field in the device. Both the improved charge collection efficiency and the low-leakage current lead to an energy resolution of 1.1 keV FWHM at 60 keV for a 2/spl times/2 mm/sup 2/ device and 2 keV for a 10/spl times/10 mm/sup 2/ device at 5/spl deg/C without any charge-loss correction electronics. For astrophysical applications, we have developed an initial prototype CdTe pixel detector based on the CdTe diode. The detector has 400 pixels with a pixel size of 625/spl times/625 /spl mu/m/sup 2/. Each pixel is gold-stud bonded to a fanout board and routed to a front end ASIC to measure pulse height information for each /spl gamma/-ray photon.