CS216884B1 - Accousto-electric converter of the capacitous type - Google Patents

Abstract

The invention solves the problem of organic substitution foil with chalcogenide amorphous layer material in an acoustic-electric capacitor converter type. Selenium-based glasses (Se) arsenic (As), and sulfur (S) are characterized by their ability accumulate charge and keep longer polarized state. Such a mó layer to replace the electret layer in acoustoelectric converters while maintaining its functional properties. The layer can be applied by steaming in vacuum.

Description

The invention relates to the use of amorphous chalcogenide materials in electrostatic acousto-electric transducers for the generation and detection of ultrasound.

Electrostatic acousto-electric transducers have been greatly improved in the last decade by the use of polarizable foils - electrets. The accumulation of charge creates permanent polarization in the film and when using a polarized film, it is not necessary to apply voltage to the converter and the field between the electrodes reaches 10 ⁶ V / m and more. Compared to piezoelectric transducers, such electret-based transducers have advantages in particular in their easy formability, in the preparation of large-area transducers, mosaic structures and the like. However, they are organic films and their preparation technology does not allow them to be made directly in the manufacture of the acoustic-electrical system.

The drawbacks of the prior art can be overcome by a capacitive type acousto-electric transducer, characterized in that an amorphous chalcogenide layer is formed between the electrodes of the transducer to create an electric field by accumulating charge, wherein the amorphous chalcogenide layer is separated from the electrodes by a dielectric layer.

By replacing the electret layer in the acoustoelectric transducer with a layer of chalcogenide material, the functional properties of the transducer are maintained and operational and manufacturing advantages are achieved. The main advantage of using amorphous chalcogenide layers is the possibility of realization by evaporation under vacuum. Such a manufacturing process allows the preparation of very thin layers and therefore operating with a smaller electric field. The advantage is that this technology is the same as used in microelectronics and therefore acoustic-electric transducers with chalcogenide layer can be made directly in integrated systems. Amorphous chalcogenide layers are glassy materials and are characterized by less acoustic losses than organic films and are therefore suitable for higher frequencies.

The main advantage of the proposed converter is the possibility of its realization in microelectronics by the usual technology of vacuum evaporation or adjustment. However, a transducer of this type can also be made by gluing powder material between the electrodes using a suitable binder. The disadvantage of gradual depolarization can be eliminated by suitable electrical wiring. The vitreous layers are characterized by less acoustic losses than organic films and the frequency range of their use is therefore much higher.

Three possible configurations of the transducer with the chalcogenide layer used are shown in the attached figures. In FIG. 1 is a system with two blocking electrodes, FIG. 2 is a single blocking electrode system; and FIG. 3 is a powder chalcogenide system.

In a particular experimental embodiment, the chalcogenide materials selenium (Si, sulfur (S), arsenic sulfide (As ₂ S ₃ ) and larzemium iselenide (AS ₂ Se ₃ j) were tested in systems suitable for the generation of ultrasound. cm ² and bonded to a sample in which 13.6 MHz ultrasound was introduced or fed in. The acelectric transducers were tested in three versions differing in combination of the dielectric and the respective layer. The chalcogenide layer 3 of 10 μΐη depth was vaporized onto one of the glasses Electrodes 1 were thrust, aluminum In the system of Fig. 2, chalcogenide 3 was ground to one of the zinc (Zn) electrodes 1 to a depth of 100 µm. The dielectric layer 2 consisted of 20 µm mica, and in the system of Fig. 3, the powdered chalcogenide was mixed with an insulating varnish 4 and deposited between dielectric layers (glass) 2 having a thickness of 150 μία. The electrodes 1 were pressurized.

The systems thus formed were polarized by connecting them to 100-500 V unidirectional voltage sources. Semiconductor chalcogenide glasses based on selenium Se, arsenic As and sulfur S are characterized by the ability to accumulate charge and thus maintain a polarized state for a longer period of time.

This characteristic varies according to the type of compound (arsenic old man As ₂ S ₃ , arsenic selenide As ₂ Se ₃ and the like) and the purity of the materials and the technology of preparation. The charge accumulation always occurs if at least one of the electrodes is a blocking electrode Due to the presence of deep containment centers, the dissolution of the bilayer is slow and, depending on the type and quality of the layer, can take from a few minutes to several days, and the polarization and depolarization processes can be accelerated by light and heat. the inverter is ready for operation and connected to a high-frequency power source generates ultrasound The optimum inverter mode in pulsed operation can be achieved by commuting a DC voltage, in which case the field in the sample consists of an external field and at the same high frequency For connecting the inverter to high-frequency voltage sources or receivers, the same conditions apply to all capacitance type inverters. The efficiency achieved by Do216 884 is the same as that of capacitive type thin-film converters with a dielectric layer permanently polarized by DC voltage.

In addition to the above-mentioned methods, converters for other frequency ranges can also be produced on this principle. If the layer thickness is chosen appropriately, the operation of the converter can be optimized for the given case.

An acousto-electric transducer with a chalcogenide layer can be advantageously used in the construction of delay lines in microelectronics, in the manufacture of complex mosaic structures for displaying acoustic fields, in the production of shaped transducers in hydroacoustics and the like.

Claims (1)

OBJECT OF THE INVENTION A capacitive-type acousto-electric transducer, characterized in that an amorphous chalcogenide layer (3) is formed between the electrodes of the transducer (1) to form an electric field by accumulating charge, the amorphous chalcogenide layer (3) being separated from the electrodes (1j by a dielectric layer). (2).