Monolayer Graphene Radiation Sensor with Backend RF Ring Oscillator Transducer

Abstract

This paper proposes a new graphene gamma- and beta-radiation sensor with a backend RF ring oscillator transducer employed to convert the change in the graphene resistivity due to ionizing irradiation into a frequency output. The sensor consists of a CVD monolayer of graphene grown on a copper substrate, with an RF ring oscillator readout circuit in which the percentage change in frequency is captured versus the change in radiation dose. The novel integration of the RF oscillator transducer with the graphene monolayer results in high average sensitivity to gamma irradiation up to 3.82 kΩ/kGy, which corresponds to a percentage change in frequency of 7.86% kGy−1 in response to cumulative gamma irradiation ranging from 0 to 1 kGy. The new approach helps to minimize background environmental effects (e.g., due to light and temperature), leading to an insignificant error in the output change in frequency of the order of 0.46% when operated in light versus dark conditions. The uncertainty in readings due to background light was analyzed, and the error in the resistance was found to be of the order of 1.34 Ω, which confirms the high stability and selectivity of the proposed sensor under different background effects. Furthermore, the evolution of the graphene’s lattice defect density due to radiation was observed using Raman spectroscopy and SEM, indicating a lattice defect density of up to 1.780 × 1011/cm2 at 1 kGy gamma radiation, confirming the increase in the graphene resistance and proving the graphene’s sensitivity. In contrast, the graphene’s defect density in response to beta radiation was 0.683 × 1011/cm2 at 3 kGy beta radiation, which is significantly lower than the gamma effects. This can be attributed to the lower p-doping effect caused by beta irradiation in ambient conditions, compared with that caused by gamma irradiation. Morphological analysis was used to verify the evolution of the microstructural defects caused by ionizing irradiation. The proposed sensor monitors the low-to-medium cumulative range of ionizing radiations ranging from 0 to 1 kGy for gamma radiation and 0 to 9 kGy for beta radiation, with high resolution and selectivity, filling the research gap in the study of graphene-based radiation sensors at low-to-medium ionizing radiation doses. This range is essential for the pharmaceutical and food industries, as it spans the minimum range for affecting human health, causing cancer and DNA damage.

Graphene-nuclear nexus: a critical review

“…IAEA recommends unmanned activities in high-risk zones to avoid any exposure of radiation [166]. For potential application in nuclear power plant, it is interesting to know that graphene-based detectors tend to degrade exposure to gamma as well as alpha and beta radiation [167][168][169][170]. In hostile environments in nuclear power plants, Mondal et al proposed gammaray tolerant flexible pressure-temperature sensor for nuclear radiation environment that could measure the pressure of range 0-62.5 kPA with sensitivity of 4.71 kPa −1 , and temperature of range 21 • C-110 • C with 2.23% resistance change per degree [171,172].…”

First-principles study on the structural properties of 2D MXene SnSiGeN4and its electronic properties under the effects of strain and an external electric field

“…The layered SnSiGeN 4 has a symmetric hexagonal structure in the x-y plane, therefore, its charge-carrier mobilities and related quantities, as shown in Table 3, are independent of the direction along which they were determined. They are, however, dependent on the energy functions of the k-point, as given in eqn ( 5)- (7). The effective masses are inversely proportional to the second derivatives of the energy functions, according to eqn (5).…”

“…Monolayer graphene has been used in gamma and beta radiation sensors, and 2D Bi 2 Se 3 has been applied in photodetectors. 7,8 Both InSe and MoTe 2 have been shown to be very effective when used in eld-effect transistors. 9,10 Moreover, hexagonal boron nitride has been applied in light-emitting diodes, and 2D WS 2 can improve the photocatalytic activity of mesoporous titania lms.…”