Integrated Thick-Film P-i-p<sup>+</sup> Structures Based on Spinel Ceramics

Abstract

Multilayered temperature/humidity sensitive thick-film p-i-p+ structures based on spinel-type semiconducting ceramics of different chemical composition Cu0.1Ni0.1Co1.6Mn1.2O4 (with p+-type of electrical conductivity), Cu0.1Ni0.8Co0.2Mn1.9O4 (with p-type of electrical conductivity) and magnesium aluminate i-type MgAl2O4 ceramics, as well as p-p+ and p-p+-p structures were fabricated and studied. Temperature-sensitive thick-film structures possess good electrophysical characteristics before and after long-term ageing test at 170 оС, the relative electrical drift being no more than 1 %. Increase of number of thick-film layers from two to three results in the improvement temperature sensitivity of thick-film structures. It is shown, that just prepared humidity-sensitive thick films in one-layered performance posses good linear dependence of electrical resistance from relative humidity without hysteresis in the range of 40-99 %. Losses of the sensitivity of these elements in time at the normal physical condition are connected with degradation process on contact area. The integrated spinel-type p-i-p+ thick-film structures show humidity-sensitivity within one-order change of electrical resistance and are stable in time. These structures are shown to be successfully applied for integrated environmental sensors.