Performance test of the silicon PIN diode with radioactive sources

Silicon PIN diodes with an active area of 1 cm × 1 cm were fabricated on a high resistivity, (100)-oriented, n-type, 380-μm thick and 5-inch silicon wafer. These diodes were originally fabricated on purpose to monitor strip sensor fabrication processes. To evaluate the performance of the silicon PIN diode, we measured the signal-to-noise ratio (SNR) and energy resolution using radioactive sources. We measured the radiation detection responses of the silicon PIN diodes and observed photopeaks from radioactive sources, Am-241, Sr-90 and Cs-137. The spectrum by simulation was compared with those of the source tests to understand the measurement results. The tests with Am-241 and Cs-137 sources used random trigger because γ fully deposits its energy in a silicon PIN diode. Another PIN diode was used for trigger purpose with Sr-90, β source. Am-241 test showed a sharp peak of 59.5 keV γ as we expected. The γ peak was used for calibration that converts ADC value into energy. We used Cs-137 source to compare a resolution at the lower energy level (32 keV γ) with 59.5 keV γ. Two different conditions were set for Cs-137; without a lead-block and with 3mm-lead-block to reduce β background. In the test of Sr-90, the SNR of the silicon PIN diode was measured to be 36.0. We present the energy resolution and the SNR of the diode measured by using the radioactive sources.