Wafer-compatible fabrication of thermally induced ultrasound emitters using nanocrystalline silicon layer

Thermal conductivity and heat capacity per unit volume for a nanocrystalline silicon (nc-Si) layer prepared by electrochemical anodization are extremely low when compared to those exhibited by single crystal silicon (c-Si). A fairly high contrast in the thermal properties between nc-Si and c-Si makes it possible to produce an efficient ultrasound emitter device based on the principle of thermo-acoustic conversion. This paper investigates the practical wafer-compatible process of this new device that uses thin SiC film as an etching mask and as well as an insulator. As previously observed in the discrete device, the fabricated device exhibits a flat frequency response.