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Piazza G.,Carnegie Mellon University | Felmetsger V.,OEM Group | Muralt P.,Eawag - Swiss Federal Institute of Aquatic Science and Technology | Olsson III R.H.,Sandia National Laboratories | Ruby R.,Avago Technologies
MRS Bulletin | Year: 2012

This article reports on the state-of-the-art of the development of aluminum nitride (AlN) thin-fi lm microelectromechanical systems (MEMS) with particular emphasis on acoustic devices for radio frequency (RF) signal processing. Examples of resonant devices are reviewed to highlight the capabilities of AlN as an integrated circuit compatible material for the implementation of RF fi lters and oscillators. The commercial success of thin-fi lm bulk acoustic resonators is presented to show how AlN has de facto become an industrial standard for the synthesis of high performance duplexers. The article also reports on the development of a new class of AlN acoustic resonators that are directly integrated with circuits and enable a new generation of reconfi gurable narrowband fi lters and oscillators. Research efforts related to the deposition of doped AlN fi lms and the scaling of sputtered AlN fi lms into the nano realm are also provided as examples of possible future material developments that could expand the range of applicability of AlN MEMS.© 2012 Materials Research Society. Source

Chowdury M.A.H.,Shahjalal University of Science and Technology | Monkman A.P.,OEM Group | Chawdhury N.,Shahjalal University of Science and Technology
Journal of Polymer Research | Year: 2011

A systematic optical study of a series of 9,9-dyoctylefluorene-2,7-diyl- dibenzothiophene-s,-s-dioxide-3,7-diyl co-polymers p(F-S)y has been performed where S unit (-dibenzothiophene-s,sdioxide-3,7diyl) varied from 15 to 50 mol%. We have investigated optical absorption, steady state and time resolved photoluminescence spectroscopy at room temperature and at low temperature. The emission band for all of these materials is red shifted from that of poly(9,9-dioctylfluorene). Except for p(F-S)50 all our material show one phosphorescence band at low temperature. Dual phosphorescence is observed for p(F-S)50 that are originated from different monomer units. Drop cast film of p(F-S)50 shows amplified spontaneous emission (ASE) effect peaking at 2.66 eV with FWHM at 5 nm. © 2011 Springer Science+Business Media B.V. Source

Lin C.-M.,University of California at Berkeley | Chen Y.-Y.,Tatung University | Felmetsger V.V.,OEM Group | Senesky D.G.,Stanford University | Pisano A.P.,University of California at Berkeley
Advanced Materials | Year: 2012

An AlN/3C-SiC composite layer enables the third-order quasi-symmetric (QS 3) Lamb wave mode with a high quality factor (Q) characteristic and an ultra-high phase velocity up to 32395 ms -1. A Lamb wave resonator utilizing the QS 3 mode exhibits a low motional impedance of 91 Ω and a high Q of 5510 at a series resonance frequency (f s) of 2.92 GHz, resulting in the highest f s·Q product of 1.61 × 10 13 Hz among the suspended piezoelectric thin film resonators reported to date. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Lin C.-M.,University of California at Berkeley | Lien W.-C.,University of California at Berkeley | Felmetsger V.V.,OEM Group | Hopcroft M.A.,University of California at Berkeley | And 3 more authors.
Applied Physics Letters | Year: 2010

Highly c -axis oriented heteroepitaxial aluminum nitride (AlN) films were grown on epitaxial cubic silicon carbide (3C-SiC) layers on Si (100) substrates using alternating current reactive magnetron sputtering at temperatures between approximately 300-450 °C. The AlN films were characterized by x-ray diffraction, scanning electron microscope, and transmission electron microscopy. A two-port surface acoustic wave device was fabricated on the AlN/3C-SiC/Si composite structure, and an expected Rayleigh mode exhibited a high acoustic velocity of 5200 m/s. The results demonstrate the potential of utilizing AlN films on epitaxial 3C-SiC layers to create piezoelectric resonant devices. © 2010 American Institute of Physics. Source

Lin C.-M.,University of California at Berkeley | Yen T.-T.,University of California at Berkeley | Felmetsger V.V.,OEM Group | Hopcroft M.A.,University of California at Berkeley | And 3 more authors.
Applied Physics Letters | Year: 2010

In this letter, temperature compensation for aluminum nitride (AlN) Lamb wave resonators operating at high temperature is presented. By adding a compensating layer of silicon dioxide (SiO2), the turnover temperature can be designed for high temperature operation by varying the normalized AlN film thickness (hAlN /λ) and the normalized SiO2 film thickness (h SiO2 /λ). With different designs of hAlN/λ and h SiO2/λ, the Lamb wave resonators were well temperature-compensated at 214 °C, 430 °C, and 542 °C, respectively. The experimental results demonstrate that the thermally compensated AlN Lamb wave resonators are promising for frequency control and sensing applications at high temperature. © 2010 American Institute of Physics. Source

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