Damp Heat Stability of ZnO:Ga Thin Films on Glass Substrate

We investigated the damp heat stability of Ga-doped ZnO (GZO) thin films grown on glass substrates. GZO thin films with thicknesses of 150 nm were grown on glass substrates by rf-magnetron sputtering. After the deposition, a damp heat stability test was performed at various temperature (50 similar to 65 degrees C) and relative humidities (80 similar to 90%) for up to 240 hr. With increasing temperature and humidity, the sheet resistance of the GZO thin films increased to a maximum of 14.2% at 65 degrees C/90% RH. The changes of surface morphology caused by damp heat were drastic and were comparable to the degradation caused by high temperature only. The effect of damp heat is discussed based on the electrical and the structural characterizations.