Generation lifetime analysis of p-n junction X-ray detector

Operation lifetime of the X-ray detector is the major factor that defines cost of detector or the actual operation cost of the detector. The purpose of this paper is to study the possibility of operation lifetime extension of the silicon x-ray detector. The study of the device's carrier generation lifetime before and after device exposed to the X-ray for 4 and 150 second at 40, 55 as well as 70 keV were conducted in this paper. The 1 mm² p-n junctions were fabricated by boron implantation process into phosphorus doped silicon wafer. A commercial x-ray source for dentist was used to generate x-ray in these experiments. The carrier generation lifetime was calculated from current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The results show that the carrier generation lifetime increased after 4 second of x-ray irradiation at all three energy conditions but decreased back close to the original value after continue exposed devices for another 150 second. However, the lowest point of the generation lifetime after 4 second of x-ray irradiation is depending on the level of energy used. The results also presented that the defects that caused by x-ray irradiation are manageable.