Analysis of Zinc Nitride Resistive Indicators under Different Relative Humidity Conditions

Zinc nitride (Zn₃N₂) is a metastable material in ambient conditions because of its high reactivity with water molecules. In this work we perform a systematic analysis of the oxidation of Zn₃N₂ layers grown by RF magnetron sputtering at room temperature. The aging and transformation of the layers toward a ZnO film is explored by means of spectroscopic ellipsometry and scanning electron microscopy for conditions with different relative humidity (RH). Accurate depth profiling by means of elastic recoil detection analysis with a time-of-flight telescope demonstrated the substitutional reaction between O and N and the important effect of the RH in this process. Because of this metastability the resistivity of the layers changes several orders of magnitude. Taking advantage of this principle, we develop electronic indicators and characterize the transformation of their electrical properties as a function of the ambient RH, finding a good correlation between the transformation time and the RH level.