A preliminary investigation on the temperature stability of selenium alloys has been carried out to determine their performance limitations in terms of properties relevant to x- ray imaging applications. The selenium properties tested as a function of temperature were the rate of crystallization, dark current, x-ray sensitivity and the residual signal. Results from crystal growth data show that the lifetime of conventional selenium can be up to 30 years of operation at 40 degrees Celsius but only about 3 years at 50 degrees Celsius. However, selenium alloys produced with a new process exhibited improved thermal stability by a factor of more than 2, with expected lifetime of up to 7 years at 50 degrees Celsius. Long term temperature cycling at 50 degrees Celsius show that the dark current remained below 50 pA/cm2 for the test period of about 100 operational days but was projected to remain below 100 pA/cm2 for up to 10 operational years. Testing under operational conditions showed a slight but reversible increase in the dark current occurred at 50 and 60 degrees Celsius, accompanied by a corresponding reversible decrease in the x-ray sensitivity in this temperature range. The loss in the x-ray sensitivity however, could be recovered by suitably increasing the operating electric field.
[1]
Andrew D. A. Maidment,et al.
Clinical evaluation of a full-field digital-projection radiography detector
,
1998,
Medical Imaging.
[2]
Kouhei Suzuki,et al.
Development and evaluation of a large-area selenium-based flat-panel detector for real-time radiography and fluoroscopy
,
1999,
Medical Imaging.
[3]
Ziad Shukri,et al.
Selenium direct-converter structure for static and dynamic x-ray detection in medical imaging applications
,
1998,
Medical Imaging.
[4]
S. Kasap,et al.
Kinetics of structural relaxations in the glassy semiconductor a–Se
,
1989
.
[5]
S. Kasap,et al.
Thermal and mechanical properties of amorphous selenium films in the glass transformation region
,
1990
.