| 摘要 |
In a semiconductor diaphragm type electro-acoustic transducer device having no necessity for a DC bias voltage applied as a result of a charge-stored layer being provide between electrodes, electro-mechanical conversion efficiency undergoes a change owing to time-dependent change in a quantity of stored electricity due to leakage of charge, and so forth. As for sensitivity of signal reception, provided by an ultrasonic array-transducer made up of the electro-acoustic transducer devices each as a basic unit, not only a main beam sensitivity undergoes drift as a result of drift in the electromechanical conversion efficiency, but also there result deterioration in an acoustic S/N ratio, and deterioration in directionality of an ultrasonic beam. In order to resolve those problems, there is provided an electro-acoustic transducer device comprising a first electrode formed on top of, or inside a substrate, a thin film using silicon or a silicon compound as a base material thereof, provided on top of the substrate, a second electrode formed on top of, or inside the thin film, a void layer provided between the first electrode and the second electrode, a charge-stored layer for storing charge given by the first electrode and the second electrode, provided between the first electrode and the second electrode, and a source electrode and a drain electrode, for measuring a quantity of electricity stored in the charge-storage layer.
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