Effect of humidity on electrical properties of thin‐film Li‐Te junction

Abstract

Relative humidity (H) ‐ current (I) characteristics were investigated on test samples of thin‐film Li‐Te junction humidity sensing devices. (Fabricated by vacuum deposition and then thermally treated for 60 min at 100°C.) The devices had 15‐V ac applied, and the H ‐ I characteristics were measured for relative humidities between 30 and 90 percent The H ‐ I characteristic curves had minima at 80 percent R.H., and were linear from 30 to 70 percent. The devices differ from conventional humistor resistive humidity sensors in that the H ‐ I characteristics has decreasing current at high R.H., decreases. This unique characteristic can be exploited for a sensor well suited to low R.H. measurements. The response time is 4 to 20 s depending on the initial R.H. and the humidity change. The H ‐ I characteristic also shows good reproducibility for relative humidities between 30 and 70 percent. Auger depth profile analysis revealed that the Li‐Te junction device is formed of an Li2O + Te surface layer, and an inner layer Li2O layer, with a boundary junction between them.