Synthesis of c-axis oriented AlN thin films on different substrates: A review

Iriarte, G.F.; Rodríguez, J. C.; Calle, F.

doi:10.1016/j.materresbull.2010.05.035

Cited by 143 publications

(107 citation statements)

References 32 publications

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“…3), down to 2° for layers thicker than 1 urn. These results are comparable with that obtained in the literature [8,10,11]. Therefore, the crystal quality for the sputtered AIN films on diamond improves as its thickness increases, up to a saturation value.…”

Section: Resultssupporting

confidence: 91%

“…1, and the average results were 3.7 nm root mean square (rms). For this low value, the AIN thin film is well oriented on the c-axis [8]. After the deposition, the average surface roughness of the AIN was 4.2 nm rms.…”

Section: Resultsmentioning

confidence: 90%

“…The main difficulties in the synthesis of AIN on diamond are not only due to the intrinsic problems at the interface between the thin layer and the substrate [1,9], but also due to the high roughness of the diamond surface [8]. The surface roughness was analyzed by AFM at different spots within the wafer, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The MCD substrates were cleaned using a standard procedure before each deposit: rinsing in pirrolidone for 5 min at 80 °C, acetone for 5 min at 60 °C and methanol in an ultrasonic bath. The sputtering conditions were optimized in order to obtain highly c-axis oriented AIN at low temperature, as described elsewhere [8]. AIN films from approximately 150 nm until 3 um were deposited on microcrystalline diamond substrates under the conditions shown in Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…In order to make the most of the AIN/diamond structure and nanolithography advantages, the thickness of the piezoelectric AIN must be optimized [7], not only in terms of crystal quality, but also in enhancing the penetration of the acoustic waves into the fast propagation substrate. However, decreasing the thickness below a certain value hinders the c-axis orientation of the film due to the interface layer [8], These aspects have been evaluated by the growth of AIN films of different thicknesses on micro crystalline diamond substrates using pulsed DC reactive sputtering at low temperature. The characterization has been done by X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM).…”

Section: Introductionmentioning

confidence: 99%

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Optimization of AlN thin layers on diamond substrates for high frequency SAW resonators

et al. 2012

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AIN/diamond heterostructures are very promising for high frequency surface acoustic wave (SAW) resonators. In their design, the thickness of the piezoelectric film is one of the key parameters. On the other hand, the film material quality and, hence, the device performance, also depend on that thickness. In this work, polished microcrystalline diamond substrates have been used to deposit AIN films by reactive sputtering, from 150 nm up to 3 um thick. A high degree of the c-axis orientation has been obtained in all cases. SAW one port resonators at high frequency have been fabricated on these films with a proper combination of the film thickness and transducer size.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimization of AlN thin layers on diamond substrates for high frequency SAW resonators

et al. 2012

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Material Parameter Extraction for Complex AlScN Thin Film Using Dual Mode Resonators in Combination with Advanced Microstructural Analysis and Finite Element Modeling

Parsapour

Pashchenko

Kurz

et al. 2019

Adv Elect Materials

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rocksalt ScN, exhibits extraordinarily high piezoelectric coefficients for a nitride material. [1,2] Since its discovery by Akiyama and co-workers, many researchers confirmed the increase of piezoelectricity in AlScN with increasing Sc content, [3][4][5][6][7][8][9][10][11] reaching a maximum at the limit of the wurtzite stability somewhere between 40% and 50% of Sc on the cation site. [2,12] The piezoelectric coefficients increase by about a factor of 4 for the case of charge per stress coefficients (d-tensor), and about a factor 2.5 for the case of charge per strain coefficients (e-tensor). Computational modeling in the frame of density functional theory (DFT) confirmed well the increase of the piezoelectric coefficients, accompanied by a decrease of the stiffness with increasing Sc content. [13,14] Even though the obtained piezoelectric coefficients are small as compared to the ones of ferroelectric thin films, AlScN may reach superior performance wherever the dielectric constant (ε) is relevant as well. This is the case for sensors, [15,16] in energy harvesting, [4,17] and in some of the applications governed by a piezoelectric coupling coefficient. [3,5] This is the case in radio frequency (RF) filters for mobile phone communication operating in the lower GHz frequency range. On the market since Accurate property determination of the piezoelectric thin film material Al(1−x)Sc(x)N is necessary for designing the next generation of radio frequency resonators in mobile communication, and for testing results of ab initio calculations. Sound velocity and piezoelectric coupling of both longitudinal and shear mode are evaluated from a single dual mode resonator. This assures a compatible set of coefficients. It is observed that AlScN thin films grew differently on small, isolated bottom electrodes.The investigated film starts growing with a slightly tilted, c-textured microstructure, and switches after 200 nm to a polycrystalline film with irregularly oriented grains having c-axis tilt angles in the range of 35°-70°, as revealed by transmission electron microscope nanodiffraction mapping. Based on this information, a finite element model (FEM) is constructed that properly reproduces the resonance behavior of the resonator. The relevant elastic and piezoelectric constants are derived by curve fitting and yield somewhat lower stiffness and higher piezoelectric coefficients than ab initio calculations published in the literature. The FEM modeling results show that the upper film part with the abnormally oriented grains is overall piezoelectric, i.e., the misoriented grains maintain the polarity projected onto the growth direction from the starting layer. Thin FilmsThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

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Flexible and Transparent Aluminum‐Nitride‐Based Surface‐Acoustic‐Wave Device on Polymeric Polyethylene Naphthalate

Lamanna

Rizzi

Guido

et al. 2019

Adv Elect Materials

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The development of wearable technology increasingly requires bendable sensing devices operating across multiple domains for opto‐electro‐mechanical and biochemical transduction. Piezoelectric materials integrated into flexible and transparent device architectures can enable multiple‐sensing platforms. It is shown that flexible and compliant surface‐acoustic‐wave (SAW) piezoelectric devices include all these features and can be applied to the human body. A flexible and transparent aluminum‐nitride‐(AlN)‐based SAW device on a thermoplastic polyethylene naphthalate (PEN) substrate, fabricated by low‐temperature sputtering deposition of a multilayered AlN‐based stack, is reported for the first time. Two resonant modes, corresponding to Rayleigh and Lamb wave propagation, are shown and compared with a control SAW device on a silicon substrate. A large transmission‐signal amplitude, up to 20 dB, is achieved for the Lamb resonance mode around 500 MHz at an acoustic velocity of 10 500 m s−1. The technology is applied to the fabrication of a wearable temperature sensor. Compared to the same piezoelectric stack and SAW technology onto silicon substrates, the AlN/PEN SAW shows better performance and a temperature coefficient frequency as high as ≈810 ppm °C−1. The potential of this flexible SAW device as a wearable temperature sensor based on Rayleigh modes is demonstrated.

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Synthesis of c-axis oriented AlN thin films on different substrates: A review

Cited by 143 publications

References 32 publications

Optimization of AlN thin layers on diamond substrates for high frequency SAW resonators

Optimization of AlN thin layers on diamond substrates for high frequency SAW resonators

Material Parameter Extraction for Complex AlScN Thin Film Using Dual Mode Resonators in Combination with Advanced Microstructural Analysis and Finite Element Modeling

Flexible and Transparent Aluminum‐Nitride‐Based Surface‐Acoustic‐Wave Device on Polymeric Polyethylene Naphthalate

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