Publications by Mohammad Fazel Parsapour Kolour

Impact of negative bias on the piezoelectric properties through the incidence of abnormal oriented grains in Al0.62Sc0.38N thin films

Paul Muralt, Thomas La Grange, Silviu Cosmin Sandu, Mohammad Fazel Parsapour Kolour, Xiao Di, Robin Nigon, Lukas Riemer

Sputter deposited A1ScN films with an Sc content of 38 at % were investigated by X-ray diffraction and electron microscopy to study the influence of the radio frequency (RF) bias on the growth of abnormally oriented grains (AOG). Scanning electron microsco ...

2020

Abnormal Grain Growth in AlScN Thin Films Induced by Complexion Formation at Crystallite Interfaces

Paul Muralt, Thomas La Grange, Silviu Cosmin Sandu, Stefan Mertin, Ramin Matloub Aghdam, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

Sputter deposited Al(1-x)ScxN thin films with a Sc content from x = 0 to 43 at% are investigated by electron microscopy in order to study and explain the formation and growth of abnormally oriented grains (AOG). It is found that the latter did not nucleate ...

Wiley-VCH Verlag2019

Growth, Integration, and Functional Characterization of AlScN Thin Films for RF MEMS Devices

Mohammad Fazel Parsapour Kolour

Mobile communication has grown explosively in recent years, leading to a strong demand for cheap, but high-performing bandpass filters with low insertion loss and smaller size. Surface acoustic wave (SAW) and thin film bulk acoustic wave (BAW) resonators r ...

EPFL2019

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

Paul Muralt, Thomas La Grange, Silviu Cosmin Sandu, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko, Kaoru Yamashita

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 an ...

WILEY2019

Growth, Properties, and Applications of Al1-xScxN Thin Films

Paul Muralt, Stefan Mertin, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

The discovery of enhanced piezoelectricity in solid solutions of AlN and ScN is certainly one of the most important events in piezoelectric MEMS. As compared to pure AlN, it brought a crucial factor 2 to 3 improvement in a number of figures of merit govern ...

IEEE2019

Free standing and solidly mounted Lamb wave resonators based on Al0.85Sc0.15N thin film

Paul Muralt, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

Lamb wave microresonators with wavelengths ...

AMER INST PHYSICS2019

Determination of elastic and piezoelectric properties of Al0.84Sc0.16N thin films

Paul Muralt, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

In this work, bar- and disk-shaped resonators were fabricated using Al(0.8)4Sc(0.16)N thin film Sensitivity analysis of the resonators' resonance frequencies with respect to the piezoelectric material parameters revealed that resonance analysis can be used ...

IEEE2018

Material Constants Extraction For Alscn Thin Films Using A Dual Mode Baw Resonator

Paul Muralt, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

Dual mode bulk acoustic wave resonators were fabricated using tilted c-axis oriented grains. In this case, longitudinal and shear modes are excited at the same time. The stiffness matrix for the tilted geometry was derived, and served to determine c(33) an ...

IEEE2018

Ex-situ AlN seed layer for (0001)-textured Al0.84Sc0.16N thin films grown on SiO2 substrates

Paul Muralt, Silviu Cosmin Sandu, Stefan Mertin, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

It is more difficult to nucleate AlN-ScN alloy thin films (AlScN) in pure (0001)-texture than it is with pure AlN thin films. AlN thus can serve as seed layer for AlScN. Equipment limitations may lead to the problem of a vacuum break between AlN and AlScN ...

Ieee2017

Enhanced piezoelectric properties of c-axis textured aluminium scandium nitride thin films with high scandium content: influence of intrinsic stress and sputtering parameters

Paul Muralt, Silviu Cosmin Sandu, Clemens Benedict Nyffeler, Gabriel Christmann, Stefan Mertin, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

Aluminium scandium nitride (ASN) exhibits a largely enhanced piezoelectric response as compared to aluminium nitride (AlN), which makes it an upcoming piezoelectric material for use in next generation RF filters, sensors, actuators and energy harvesting de ...

Ieee2017

Effective SAW excitation on non-piezoelectric substrate using AlScN piezoelectric thin film BAW/SAW hybrid transducer

Paul Muralt, Sylvain Ballandras, Mohammad Fazel Parsapour Kolour, Vladimir Pashchenko

Acoustic delay lines based on Al0.85Sc0.15N thin film hybrid transducers were investigated by finite element modeling. It was found that an acoustic impedance matching between transducer and non-piezoelectric substrate material plays a crucial role to effi ...

Ieee2017