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This article presents the design, fabrication, and characterization of an integrated differential dosimeter based on the mismatch of two identical field oxide MOS transistors (FOXFETs). This dosimeter was fabricated in a high-voltage $0.35~\mu \mathrm {m}$ CMOS process, where the FOXFET and the biasing circuit were integrated in the same chip. The FOXFET as a single device and the whole circuit as an integrated differential sensor were characterized regarding its response to both radiation and temperature. The differential sensor showed low temperature sensitivity, 320 times lower than that of the single FOXFET, while it also showed a reduction in radiation sensitivity only in a factor of 1.6. These results drastically improved the temperature error factor (TEF), calculated to be 23 mrad/°C. Moreover, the bias-controlled cycled measurement technique was successfully implemented by improving the dose range up to 9.4 krad. Finally, the temperature rejection performance was assessed in real-time measurements during exposure to radiation, and the sensitivity of the dosimeter showed no change with temperature.

In this paper we present a new dosimeter based on a pair of thick gate oxide MOSFET sensors. A differential circuit topology with a feedback loop provides stabilized output with selectable sensitivity amplification for real time in vivo dosimetry. Radiation response shows a wide linear output range and an effective thermal rejection. These properties make this circuit suitable for dose control in radiotherapy applications. Fil: Garcia Inza, Mariano Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina Fil: Carbonetto, Sebastián Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina Fil: Lipovetzky, José. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Faigon, Adrian Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina

This paper presents a new technique to build MOS dosimeters using unmodified standard CMOS processes. The devices are n-channel MOS transistors built with the regular Field Oxide as a thick radiation-sensitive gate. The devices were fabricated in two different commercial m CMOS processes, gate oxide thicknesses of nm and nm. Responsivities up to 4.4 mV/rad with positive bias, and 1.7 mV/rad with zero gate bias were obtained in the thicker oxides. The effect of charge trapped in the oxide and interface states on the shift in the threshold voltage are analyzed. Fil: Lipovetzky, José. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: García Inza, Mariano Andrés. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Carbonetto, Sebastián Horacio. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Carra, Martin Javier. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina Fil: Redin, Eduardo Gabriel. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina Fil: Sambuco Salomone, Lucas Ignacio. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina Fil: Faigon, Adrián Néstor. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Through the injection of a Fowler-Nordheim tunnel current or the inversion of oxide fields during irradiation (Radiation-Induced Charge Neutralization), the oxide charge trapped in thick-oxide (300 nm) commercial RADFETs, often called QOT could be erased. Novel trapped-hole and interface characteristics were observed after treatments of this type at high doses. With both erasure techniques, it was possible only to neutralize a fraction of the oxide trapped charge. A non negligible amount of charge and border traps is deemed here to be “intractable”. That adjective an a symbol, QIN, are introduced for the first time in this paper. Later sections discuss the possible impact of these results. The conclusion for dosimetry is that a “reusable RADFET” dosimeter, working up to an unprecedented dose before wearing out, may be a practical possibility.