Electrical and mechanical behaviour of improved platinum on ceramic bolometers

Bolometers using Au meanders on a mica substrate under irradiation suffered severe degradation before 0.01 dpa. Therefore this work was undertaken to examine alternative more radiation resistant bolometer versions. Basic prototypes from CIEMAT with sputtered Pt meander sensors on Al2O3 and AlN ceramic substrates were tested during electron and neutron irradiation at CIEMAT and SCK/CEN Mol. Results up to 0.01 dpa showed acceptable behaviour of both substrates and better radiation resistance response of Pt compared with Au. However the electrical connection between terminals and meander was identified as a weak point of the design. In addition the electrical response of the sputtered metal films was observed to degrade at high temperatures (≥900 deg. C) as a consequence of the discontinuity of the thin metal film and the formation of Pt islands. Here we report on an improved prototype, with reduced meander area, enhanced Pt film quality and adhesion, and better electrical connections. The improved bonding and hence stability of the meander was obtained by sputtering and thermally evaporating a Pt sensor on to polished surfaces of AlN and Al2O3 substrates. The thermal stability of the sputtered Pt deposit has also been followed using ESEM during in situ sample heating. After vacuum annealing at 400 deg. C, these new prototypes were electrically characterized