Research on preparations of precise-resistance thin-film materials having higher resistivity with zero-temperature dependence

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In this research, preparations of novel thin film resistance materials which have small temperature coefficient of resistance (TCR) and higher resistivities compared with those of the usual materials were investigated. Firstly, effects of nitrogen, oxygen and substrate temperatures on electrical properties of ZnO : In thin films were investigated. The TCR showed minimum value when In_2O_3 was added to ZnO at 9 wt%. The resistivities decreased with increasing of N_2 partial pressure, whereas the resistivities increased with the increasing of N_2 partial pressure when it was over 20 %. Carrier concentration of the ZnO based films became high as 10^<20>cm^<-3> when Al_2O_3 was added to ZnO at 2 wt%. Resistivity of the films increase from 10^<-3> to 1 Ω・cm by adding Cu to the films, and their TCR became low within 100 ppm/℃ Moreover, resistivity of the ZnO films increased from 10^<-1> to 10^3 Ω・cm by mixing MgO to the films. Degenerated Al_2O_3 added ZnMgO films kept high carrier concentration, whereas Hall mobility of them was extremely low and their resistivity increased to about 3×10^<-3> Ω・cm. Their TCR showed within 50 ppm/℃. The resistivities showed much higher value when the substrate material was changed from sapphire single crystals to quartz glasses.