Consideration of the Leakage-Current and the Radiation-Response Characteristics of Silicon PIN Detectors with Different N-Type Substrates and their Application to a Personal -ray Dosimeter

Abstract

The effects of resistivity and crystal orientation on the leakage-current and the radiation-response characteristics of silicon PIN detectors have been studied. A high-resistive substrate (>8 kΩ·cm) shows a larger leakage current than a low-resistive one (<4 kΩ·cm) at low reverse bias because of its wider depletion width, but the opposite result is seen at high reverse bias. We think that the thermionic field emission (TFE) current increases at high reverse bias for a low-resistive substrate. The detector with a (111)-oriented substrate exhibits leakage current chacteristics comparable to those of the (100)-oriented one when the resistivity of the substrate is 3.8 kΩ·cm. An X-ray beam irradiation test showed that the output current of the detector with the (111)-oriented substrate was 20 % higher than that of the (100)-orientated one and that the result was independent of the resistivity of the substrate. Based on the results, we fabricated a silicon PIN detector for a personal γ ray dosimeter operated at 3 V with a substrate having a (111) orientation and a resistivity of 3.8 kΩ·cm, and we assembled it with read-out integrated circuit. Our detector was sensitive to Cs 137 natural γ rays and showed a good linearity in the exposure rate.

A new technique for measuring the leakage current in Silicon Drift Detector based X-ray spectrometer—implications for on-board calibration

“…However, the accumulated space radiation dose induced leakage current is expected to increase with time due to silicon bulk damage caused by the high energy particles. Such bulk damage will degrade the energy resolution substantially [32][33][34] which can be quantified by measuring the leakage current on-board. It should be noted that the exposure to the space radiation does not only increases the leakage current, but also reduces the charge collection efficiency due to charge trapping [35] of the bulk devices.…”

Design and Characterization of a Compact Radiation Monitor for Space Rockets

“…Leakage current (𝐽 𝑅 ) of PIN diodes is commonly described in literature as a combination of the diffusion current (𝐽 𝐷𝑖𝑓𝑓 ) and the generation current (𝐽 𝐺𝑒𝑛 ) as shown in Equation (1) [12].…”

“…where q is the charge of the electron, D p is the diffusion coefficient of silicon, τ p is the minority carrier lifetime, τ e is the effective lifetime, n i is the intrinsic carrier concentration, N A is the doping concentration and W is the depletion width. The depletion width increases with the square root of the reverse bias voltage as described by Equation 2 [12].…”