SURFACE MODIFICATION OF MGO SUBSTRATES FROM AQUEOUS EXPOSURE - AN ATOMIC-FORCE MICROSCOPY STUDY

Cleaved MgO was subjected to fluid and gaseous chemical attack by wate r at or near ambient temperature. The exposure experiments were design ed to mimic the variety of conditions that MgO may encounter as a subs trate material in thin film technology. The resultant surface alterati ons were monitored with contact mode atomic force microscopy. It was f ound that MgO was relatively inert, at the near-atomic scale of detail , when the relative humidity of the gaseous phase was below 30%. When the humidity exceeded 30%, degradation was initiated at sites of low c oordination (corners and steps). These results would indicate that, wh en handling MgO as a substrate for thin film technology, the processin g environment must be carefully controlled to exclude bulk water and m aintain humidity below 30%.