New Operating Mode of Nanocrystalline Silicon Ultrasonic Emitters for Use as Audio Speakers

概要

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To extend the technological potential of thermally induced ultrasonic emissions from the nanocrystalline silicon (nc-Si) devices we reported previously a driving mode suitable for operation in the audio-band has been studied. The device is composed of a patterned surface electrode, an nc-Si layer, and a single-crystalline silicon substrate. The acoustic emission is based on efficient heat exchange at the surface-air interface in which the surface temperature fluctuations induced by electrical input are quickly transferred to air due to the complete thermal insulating properties of the underlying nc-Si layer. In the proposed driving mode, a dc-superimposed input is sent into the surface electrode. In contrast to the conventional driving mode using a simple ac-signal input, the device efficiently emits the acoustic output signal at the same frequency as the input signal. A linear relationship between the input voltage and the output amplitude has been confirmed as expected. This driving mode is applicable to the operation of an audio-band speaker.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-04-15