Effect of Dielectric Charging on Capacitance Change of an SOI Based CMUT

Title:Effect of Dielectric Charging on Capacitance Change of an SOI Based CMUT

Volume: 6 Issue: 1

Author(s): Tugrul Zure and Sazzadur Chowdhury

Affiliation:

Keywords: Capacitance, CMUT, dielectric charging, leakage current, MEMS, microfabrication, SOI.

Abstract: Effect of dielectric charging on the performance of SOI based Capacitive Micromachined Ultrasonic Transducers (CMUT) has been investigated. Measurements on an SOI based CMUT show that that the capacitance change as a function of DC bias is considerably higher than analytically calculated values. Investigation shows that this deviation in capacitance from analytically calculated values is due to the combined effects of different dielectric charging phenomena due to a strong electric field, trap charges in the SOI oxide layer, the charge motion associated with the leakage current through the buried oxide layer, and the air in the CMUT cavity. Additionally, this charging effect degrades the transduction efficiency as the induced polarization reduced the effective bias across the CMUT. It is concluded that the buried oxide (BOX) layers in SOI wafers are not suitable for use as dielectric spacers in electrostatic MEMS devices.

Cite this article as:

Zure Tugrul and Chowdhury Sazzadur, Effect of Dielectric Charging on Capacitance Change of an SOI Based CMUT, Micro and Nanosystems 2014; 6 (1) . https://dx.doi.org/10.2174/187640290601140919144840