Piezoelectric effects of single-crystal GaAs and multi-layered Al x Ga 1-x As/GaAs material measured by the Michelson interferometer

Abstract: Kheanumkeaw, P., Muensit, S. and Aiyarak, P. The inverse piezoelectric effect, in which the strains were electrically induced, in a single crystal of GaAs and in a multilayer structure of Al x Ga 1-x As/GaAs was measured using a simple optical system, i.e., Michelson interferometer. An ac driving voltage was applied to the sample to produce a change in the order of 10 -13 m in sample thickness. These changes were detected by the optical system to give the sample displacement as a function of applied driving voltage. The slope of the plot of this relationship led to the piezoelectric coefficients of (2.8±0.1)× × × × ×10 -12 and (3.9±0.1)× × × × ×10 -12 m/V for GaAs and Al x Ga 1-x As/GaAs, respectively. The first agreed well with reported values and the latter was the first report for Al x Ga 1-x As/GaAs. Owing to the equality for the inverse effect and the direct effect, in which an electric field can be mechanically induced, it is anticipated that in the absence of external electric field, the internal piezoelectric field can be induced in the multi-layered semiconductor. Piezoelectric effects of single-crystal GaAs and multi-layere

รูปแบบการจัดวางตัวทำงานเพียโซอิเล็กทริกและการเคลื่นที่ของคลื่นในมอเตอร์อัลตราโซนิคแบบเชิงเส้นโค้ง

Thailand Research Fund (TRF

Piezoelectric coefficients of gallium arsenide, gallium nitride and aluminium nitride

"1998"--T.p.Thesis (PhD)--Macquarie University, School of Mathematics, Physics, Computing and Electronics, 1999.Includes bibliographical references.Introduction -- A Michelson interferometer for measurement of piezoelectric coefficients -- The piezoelectric coefficient of gallium arsenide -- Extensional piezoelectric coefficients of gallium nitrides and aluminium nitride -- Shear piezoelectric coefficients of gallium nitride and aluminium nitride -- Electrostriction in gallium nitride, aluminium nitride and gallium arsenide -- Summary and prognosis.The present work represents the first use of the interferometric technique for determining the magnitude and sign of the piezoelectric coefficients of III-V compound semiconductors, in particular gallium arsenide (GaAs), gallium nitride (GaN), and aluminium nitride (AIN). The interferometer arrangement used in the present work was a Michelson interferometer, with the capability of achieving a resolution of 10⁻¹³ m. -- The samples used were of two types. The first were commercial wafers, with single crystal orientation. Both GaAs and GaN were obtained in this form. The second type of sample was polycrystalline thin films, grown in the semiconductor research laboratories at Macquarie University. GaN and AIN samples of this type were obtained. -- The d₁₄ coefficient of GaAs was measured by first measuring the d₃₃ value of a [111] oriented sample. This was then transformed to give the d₁₄ coefficient of the usual [001] oriented crystal. The value obtained for d₁₄ was (-2.7 ± 0.1) pmV⁻¹. This compares well with the most recent reported measurements of -2.69 pmV⁻¹. The significance of the measurement is that this represents the first time this coefficient has been measured using the inverse piezoelectric effect. -- For AIN and GaN samples, the present work also represents the first time their piezoelectric coefficients have been measured by interferometry. For GaN, this work presents the first reported measurements of the piezoelectric coefficients, and some of these results have recently been published by the (Muensit and Guy, 1998). The d₃₃ and d₃₁ coefficients for GaN were found to be (3.4 ± 0.1) pmV⁻¹ and (-1.7 ± 0.1) pmV⁻¹ respectively. Since these values were measured on a single crystal wafer and have been corrected for substrate clamping, the values should be a good measure of the true piezoelectric coefficients for bulk GaN. -- For AIN, the d₃₃ and d₃₁ coefficients were found to be (5.1 ± 0.2) pmV⁻¹, and (-2.6 ± 0.1) pmV⁻¹ respectively. Since these figures are measured on a polycrystalline sample it is quite probable that the values for bulk AIN would be somewhat higher.The piezoelectric measurements indicate that the positive c axis in the nitride films points away from the substrate. The piezoelectric measurements provide a simple means for identifying the positive c axis direction. -- The interferometric technique has also been used to measure the shear piezoelectric coefficient d₁₅ for AIN and GaN. This work represents the first application of this technique to measure this particular coefficient. The d₁₅ coefficients for AIN and GaN were found to be (-3.6 ± 0.1) pmV⁻¹ and (-3.1 ± 0.1) pmV⁻¹ respectively. The value for AIN agrees reasonably well with the only reported value available in the literature of -4.08 pmV⁻¹. The value of this coefficient for GaN has not been measured. -- Some initial investigations into the phenomenon of electrostriction in the compound semiconductors were also performed. It appears that these materials have both a piezoelectric response and a significant electrostrictive response. For the polycrystalline GaN and AIN, the values of the M₃₃ coefficients are of the order of 10⁻¹⁸ m²V⁻². The commercial single crystal GaN and GaAs wafers display an asymmetric response which cannot be explained.Mode of access: World Wide Web.Various pagings il

Theory and measurements for 0-3 BaTiO3/PVDF composites

This work extended the range of material properties by fabricating the BaTiO3 /PVDF composite. In order to obtain the 0-3 composite without the interconnectivity of the ceramic powders, a low volume fractionof 0.3 of barium titanate (BaTiO3) was filled in a matrix of polyvinylidene fluoride (PVDF) and the mixture was homogeneously stirred. The composite was shaped into a sheet form by a tape casting method. Themicrostructure of the composite was observed using scanning electron microscopy (SEM) which revealed that the connectivity of the composite was mainly 0-3. Subsequently, theoretical models and equations wereapplied to the composite for comparisons with measurements. The density and heat capacity of the composites were experimentally obtained to be 3.21103 kg/m3 and 3021.7 J/kg oC, respectively. The compositewas corona poled before the test of dielectric response. Its 1 kHz-dielectric constant and dielectric loss at room temperature were 11.5 and 0.21, respectively. The good dielectric combined with the flexibility of thematerial implies that the composite is attractive for electronic applications where a light, environmentally friendly, ease to fabricate and low-cost device is required

การลดจำนวนตัวทำงานเพียโซอิเล็กทริกและพฤติกรรมของคลื่นเคลื่อนที่ในมอเตอร์อัลตราโซนิค : รายงานวิจัยฉบับสมบูรณ์โครงการ

Office of the Higher Education CommissionThailand Research Fun

Electromechanical Effects in Gallium Nitride

There is currently intense interest in the properties of several of the III-V semi-conductors. Of these, gallium nitride (GaN) is currently attracting greatest interest. This is because of its large band-gap, which gives it potential for application in opto-electronic devices operating in the blue region of the spectrum. Due to its crystal structure, gallium nitride has spontaneous polarization and is piezoelectric. The piezoelectric field in strained GaN can have a significant effect on its properties in electronic devices and indeed the effect has been exploited in this area. We have used an interferometric technique to measure the field induced strain in thin GaN films, leading to values for the d33 piezoelectric coefficient. The measurements have been made both for sputtered polycrystalline films and for commercial wafers which have single crystal orientation. We have also found that the measured piezoelectric coefficient varies with an applied bias field. This suggests that GaN also possesses a significant electrostrictive response and a value for the electrostrictive coefficient M33 has been deduced from the data.6 page(s

Piezoelectricity of 1-3 PZT/epoxy composites

4 page(s

Piezoelectric effects of single-crystal GaAs and multi-layered AlxGa1-xAs/GaAs material measured by the Michelson interferometer

The inverse piezoelectric effect, in which the strains were electrically induced, in a single crystal of GaAs and in a multilayer structure of AlxGa1-xAs/GaAs was measured using a simple optical system, i.e., Michelson interferometer. An ac driving voltage was applied to the sample to produce a change in the order of 10-13 m in sample thickness. These changes were detected by the optical system to give the sample displacement as a function of applied driving voltage. The slope of the plot of this relationship led to the piezoelectric coefficients of (2.8±0.1)×10-12 and (3.9±0.1)×10-12 m/V for GaAs and AlxGa1-xAs/GaAs, respectively. The first agreed well with reported values and the latter was the first report for AlxGa1-xAs/GaAs. Owing to the equality for the inverse effect and the direct effect, in which an electric field can be mechanically induced, it is anticipated that in the absence of external electric field, the internal piezoelectric field can be induced in the multi-layered semiconductor

Phase and morphology evolution of (Na1-xKx)NbO3 powders related to calcinations and K2CO3 content

Sodium-potassium niobate ((Na1-xKx)NbO3) powders with x = 0.2, 0.4, 0.6 and 0.8 were prepared following the conventional mixed oxide method and characterized by TG-DTA, XRD and SEM techniques.The effects of calcination temperature, dwell time and K2CO3 content on phase formation behavior and morphology of the powders were investigated. The calcination temperature and dwell time were found tohave a pronounced effect on the phase formation of the calcined sodium-potassium niobate powders. It was found that the crystallized phase depended on calcination conditions. The high calcination temperature andlong dwell time clearly favored particle growth and the formation of large and hard agglomerates. All the (Na1-xKx)NbO3 powders showed a similar orthorhombic phase structure. The K2CO3 content significantlyaffected the calcination temperature and particle size and shape. Large particle size, cubic shape and a lower calcined condition were observed in (Na1-xKx)NbO3 powder with low K2CO3 content (x = 0.2)

Phase development, densification and dielectric properties of (0.95-x)Na_0.5K_0.5NbO₃ - 0.05LiTaO₃ - x LiSbO₃ lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics in the system (0.95-x) Na_0.5K_0.5NbO₃ - 0.05LiTaO₃ - x LiSbO₃, x = 0-0.1, were synthesized by a reaction-sintering method. The effects of the content of LiSbO₃, and the sintering temperature on phase-development, microstructure and dielectric properties of the samples were investigated. Additions of LiSbO₃ produced a change in crystal system from orthorhombic to tetragonal. The additive reduced the temperature at which secondary recrystallisation occurred, and also affected average grain size and dielectric constant. A sintering temperature of 1050^oC (for 2 h) was the optimum for this system in order to achieve a high density and high dielectric constant. A maximum dielectric constant of 1510 was recorded for the x = 0.04 composition