Radiation hardness characteristics of Si-PIN radiation detectors

Abstract

The Korea Atomic Energy Research Institute (KAERI) has fabricated Si-PIN radiation detectors with low leakage current, high resistivity (>11kΩcm) and low capacitance for high-energy physics and X-ray spectroscopy. Floating-zone (FZ) 6-in. diameter N-type silicon wafers, with 〈111〉 crystal orientation and 675μm thick, were used in the detector fabrication. The active areas are 3mm×3mm, 5mm×5mm and 10mm×10mm. We used a double deep-diffused structure at the edge of the active area for protection from the surface leakage path. We also compared the electrical performance of the Si-PIN detector with anti-reflective coating (ARC). For a detector with an active area of 3mm×3mm, the leakage current is about 1.9nA and 7.4nA at a 100V reverse bias voltage, and 4.6pF and 4.4pF capacitance for the detector with and without an ARC, respectively. In addition, to compare the energy resolution in terms of radiation hardness, we measured the energy spectra with 57Co and 133Ba before the irradiation. Using developed preamplifiers (KAERI-PA1) that have ultra-low noise and high sensitivity, and a 3mm×3mm Si-PIN radiation detector, we obtained energy resolutions with 122keV of 57Co and 81keV of 133Ba of 0.221keV and 0.261keV, respectively. After 10, 100, 103, 104 and 105Gy irradiation, we tested the characteristics of the radiation hardness on the Si-PIN radiation detectors in terms of electrical and energy spectra performance changes. The fabricated Si-PIN radiation detectors are working well under high dose irradiation conditions.