Charging effects in electrostatically-actuated membrane devices

We have observed the effects of electrical charging in the Mechanical Anti-Reflection Switch (MARS) device for some time. The MARS device has an membrane that is pulled toward the substrate by application of an electrical bias, and thereby produces optical modulation. Under constant bias MARS devices with insulating membranes exhibit a slow (minutes to hours) change in air gap. We have now determined that this is due to ionization in the air gap, and that the effect can be greatly reduced by placing the device in an argon atmosphere. It is postulated that the effect is due to the formation of a space charge region in the air gap adjacent to the membrane.