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

Kihara, Takashi; Hirota, Jun; Koshida, Nobuyoshi

doi:10.1109/sensor.2003.1215586

Cited by 7 publications

(6 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The nc-PS device exhibits many advantageous features over conventional one such as piezoceramic transducers, for example, flat frequency response over a wide range, 4,5) ideal acoustic pulse emission under pulse operation, [6][7][8] availability for arrayed integration and standard silicon process compatibility for device fabrication. 9,10) To understand the mechanism of this thermoacoustic effect in more detail, dynamic thermal analyses have been conducted in this study. The effect of the heat capacity of the surface heater electrode on the acoustic output is analyzed using a high-speed radiation thermometer.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Thermally Induced Ultrasonic Emission from Nanocrystalline Porous Silicon Device under Impulse Operation

Watabe¹,

Honda²,

Koshida

2006

jjap

View full text Add to dashboard Cite

To clarify the mechanism of thermoacoustic effects in a nanocrystalline porous silicon (nc-PS) device, ultrasonic emission characteristics have been investigated in relation to dynamic behavior. The nc-PS ultrasonic emitter is composed of a surface heater electrode, an nc-PS layer, and a single-crystalline silicon (c-Si) substrate. Due to a completely flat frequency response, this device emits an ideal impulse acoustic output with no reverberations for pulse driving. The relationship between acoustic output and transient surface temperature change can be well interpreted quantitatively by taking the heat capacity of the heater electrode into account. The experimental fact that the transient surface electrode temperature change is induced uniformly over the whole range of the emission area ensures the directivity of the acoustic pulse output.

show abstract

Section: Introductionmentioning

confidence: 99%

Characteristics of Thermally Induced Ultrasonic Emission from Nanocrystalline Porous Silicon Device under Impulse Operation

Watabe¹,

Honda²,

Koshida

2006

jjap

View full text Add to dashboard Cite

show abstract

“…3) There are many advantageous features over the conventional piezoceramic transducers in the nc-PS device: flat frequency response over a wide range, 4,5) ideal acoustic emission under impulse drive, 6,7) availability for arrayed integration, and standard silicon process compatibility for device fabrication. 8) Due to these functional features, a three-dimensional ultrasonic image sensor, an ultrasonic speaker, and a microactuator have been developed. [9][10][11] The key factor of this device is the thermal effusivity ðCÞ 1=2 of the nc-PS layer, because the theoretical acoustic output is inversely proportional to the ðCÞ 1=2 value.…”

Section: Introductionmentioning

confidence: 99%

Effect of Bilayer Structure on the Long-Term Stability of Nanocrystalline Porous Silicon Ultrasonic Emitter

Watabe¹,

Honda²,

Koshida³

2007

jjap

View full text Add to dashboard Cite

Due to a strong quantum confinement effect, both the thermal conductivity and heat capacity per unit volume C of nanocrystalline porous silicon (nc-PS) are extremely lowered in comparison to those of single-crystalline silicon (c-Si). This high contrast between the thermal properties of nc-PS and c-Si makes it possible to produce an efficient ultrasound emitter device based on interfacial thermoacoustic transfer with no mechanical surface vibrations. The most important parameter of this device is the thermal effusivity ðCÞ 1=2 of the nc-PS layer, since the theoretical acoustic output is in inversely proportional to ðCÞ 1=2 . To stabilize the acoustic output by suppressing possible change in ðCÞ 1=2 during a long-term operation, a bilayer structure is introduced into the nc-PS layer in this work. Due to the increased stability against oxidation, the device operates for a long time without any significant degradation. The observed long-term stability ensures the applicability of this emitter in functional acoustic devices such as sensors, speakers, and actuators.

show abstract

“…3) There are many advantageous features over the conventional piezoceramic transducers in nc-PS devices: a flat frequency response over a wide range, 4,5) an ideal acoustic pulse emission during pulse operation, 6,7) availability for arrayed integration, and standard silicon process compatibility for device fabrication. 8) Due to these functional features, a three-dimensional (3-D) ultrasonic image sensor, an ultrasonic speaker, and a microactuator have been developed. [9][10][11] One of the most important issues for a stable operation of this device is to keep the thermal effusivity ðCÞ 1=2 of the nc-PS layer constant, since the theoretical acoustic output is inversely proportional to ðCÞ 1=2 , which depends on the porosity, surface oxidation, and pore-size distribution of the nc-PS layer.…”

Section: Introductionmentioning

confidence: 99%

Effects of Thermal Effusivity in Nanocrystalline Porous Silicon on Long-Term Operation of Thermally Induced Ultrasonic Emission

Watabe¹,

Honda²,

Koshida³

2007

jjap

View full text Add to dashboard Cite

Due to a strong quantum confinement effect, both the thermal conductivity and heat capacity per unit volume C of nanocrystalline porous silicon (nc-PS) are extremely lower than those of single-crystalline silicon (c-Si). This high contrast between the thermal properties of nc-PS and c-Si makes it possible to produce an efficient ultrasound emitter device for various sensors, speakers, and actuators. The most important parameter in this device is assumed to be the thermal effusivity ðCÞ 1=2 of nc-PS, since the theoretical acoustic output is inversely proportional to the ðCÞ 1=2 of the nc-PS layer. To confirm this assumption, the output stability during a long-term operation has been studied in relation to a change in ðCÞ 1=2 . The obtained experimental results indicate that the acoustic output deteriorates with a gradual increase in ðCÞ 1=2 due to the oxidation of nc-PS and that an appropriate nanostructure control with a passivated surface against oxidation is the key issue for obtaining a practical operation time.

show abstract

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

Cited by 7 publications

References 8 publications

Characteristics of Thermally Induced Ultrasonic Emission from Nanocrystalline Porous Silicon Device under Impulse Operation

Characteristics of Thermally Induced Ultrasonic Emission from Nanocrystalline Porous Silicon Device under Impulse Operation

Effect of Bilayer Structure on the Long-Term Stability of Nanocrystalline Porous Silicon Ultrasonic Emitter

Effects of Thermal Effusivity in Nanocrystalline Porous Silicon on Long-Term Operation of Thermally Induced Ultrasonic Emission

Contact Info

Product

Resources

About