Abstract: We evaluate the use of the thick buried oxide (BOX) of Fully Depleted Silicon-on-Insulator (FD-SOI) transistors for Total Ionizing Dose (TID) measurements in a radiotherapy application. The devices were fabricated with a custom process in UniversitC) Catholique de Louvain (UCL) which allows to make accumulation mode PMOS transistors and inversion mode NMOS transistors. We characterized the temperature behavior of these devices and the response under X-ray radiation produced by an Elekta radiotherapy linear accelerator, and compared the obtained dose sensitivity to other published works. Taking advantage of these devices, an ultra low power MOS ionizing dose sensor, or MOS dosimeter, with inherent temperature compensation is presented. This dosimeter achieved a sensitivity of 154 mV/Gy with a temperature error factor of 13 mGy/°C and a current consumption below 1 nA.

Abstract: New double perovskites LaPbMSbO₆, where M²⁺ = Mn²⁺, Co²⁺, and Ni²⁺, were synthesized as polycrystals by an aqueous synthetic route at temperatures below 1000 ^°C. All samples are monoclinic, space group P2₁/n, as it is observed from Rietveld analysis of X-ray powder diffraction patterns. The distribution of M²⁺ and Sb⁵⁺ among the two octahedral sites have 3% of disorder for M²⁺ = Ni²⁺, whereas for M²⁺ = Mn²⁺ and Co²⁺ less disorder is found. The three samples have an antiferromagnetic transition, due to the antiferromagnetic coupling between M^{2 +} through super-superexchange paths M²⁺-O^2--Sb⁵⁺-O^2--M²⁺. Transition temperatures are low: 8, 10 and 17 K for Mn²⁺, Co²⁺, and Ni^{2 +} respectively, as a consequence of the relatively long distances between the magnetic ions M²⁺. Besides, for LaPbMnSbO₆ a small transition at 45 K was found, with ferrimagnetic characteristics, possibly as a consequence of a small disorder between Mn²⁺ and Sb⁵⁺. This disorder would give additional and shorter interaction paths: superexchange Mn²⁺-O^2--Mn²⁺.