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Katardjiev, Ilia
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Publications (10 of 129) Show all publications
Moreira, M. A., Törndahl, T., Katardjiev, I. & Kubart, T. (2015). Deposition of highly textured AlN thin films by reactive high power impulse magnetron sputtering. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 33(2), Article ID 021518.
Open this publication in new window or tab >>Deposition of highly textured AlN thin films by reactive high power impulse magnetron sputtering
2015 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 33, no 2, article id 021518Article in journal (Refereed) Published
Abstract [en]

Aluminum nitride thin films were deposited by reactive high power impulse magnetron sputtering (HiPIMS) and pulsed direct-current on Si (100) and textured Mo substrates, where the same deposition conditions were used for both techniques. The films were characterized by x-ray diffraction and atomic force microscopy. The results show a pronounced improvement in the AlN crystalline texture for all films deposited by HiPIMS on Si. Already at room temperature, the HiPIMS films exhibited a strong preferred (002) orientation and at 400 degrees C, no contributions from other orientations were detected. Despite the low film thickness of only 200 nm, an x-scan full width at half maximum value of 5.1 degrees was achieved on Si. The results are attributed to the high ionization of sputtered material achieved in HiPIMS. On textured Mo, there was no significant difference between the deposition techniques.

National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-257046 (URN)10.1116/1.4907874 (DOI)000355739500055 ()
Available from: 2015-06-29 Created: 2015-06-29 Last updated: 2017-12-04Bibliographically approved
Kubart, T., Törndahl, T., Moreira, M. & Katardjiev, I. (2015). Highly textured AlN thin films on Si by reactive High Power Impulse Magnetron Sputtering. In: 42nd ICMCTF 2015 International Conference on Metallurgical Coatings and Thin Films, 20–24 April, San Diego, USA: C5.  Thin Films for Active Devices. Paper presented at 42nd ICMCTF 2015 International Conference on Metallurgical Coatings and Thin Films, 20–24 April, San Diego, USA.
Open this publication in new window or tab >>Highly textured AlN thin films on Si by reactive High Power Impulse Magnetron Sputtering
2015 (English)In: 42nd ICMCTF 2015 International Conference on Metallurgical Coatings and Thin Films, 20–24 April, San Diego, USA: C5.  Thin Films for Active Devices, 2015Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Piezoelectric AlN films for electroacoustic devices are typically deposited by magnetron sputtering. Sputtering is compatible with standard microelectronic fabrication processes and requires lower deposition temperatures than other techniques. In order to enhance the texture of AlN, metal seed layers, such as molybdenum, are usually used. Low temperature growth of AlN films for devices where the seed layer cannot be used is challenging.

Here we report on the growth of thin textured (002) AlN layers directly on Si substrates without any metal seed layer. The films were deposited by reactive High Power Impulse Magnetron sputtering (HiPIMS) from an aluminium target in argon/nitrogen atmosphere. Because in HiPIMS very high degree of ionization of the sputtered material is achieved, this technique provides highly ionized flux to the substrate and thus promotes surface diffusion. Moreover, nitrogen dissociation which occurs in the high density HiPIMS plasma increases reactivity of the nitrogen. For comparison, pulsed DC sputtering was also performed under identical conditions.

We show that for 200 nm thick AlN films grown on (100) Si, the HiPIMS process produces well textured (002) films already at room temperature while the pulsed DC films are very poor. At 400°C, which is the optimal temperature for pulsed DC deposition, the HiPIMS films are superior with the FWHM value of 5.1 and 14.2° for the HiPIMS and pulsed DC, respectively. No appreciable stresses were observed in the films. The HiPIMS deposition process is more robust than standard DC sputtering and provides sufficient energy input even for configurations with relatively large target-to-substrate distance. It is therefore suitable also for co-sputtering of ternary nitrides based on AlN. 

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-269737 (URN)
Conference
42nd ICMCTF 2015 International Conference on Metallurgical Coatings and Thin Films, 20–24 April, San Diego, USA
Available from: 2015-12-18 Created: 2015-12-18 Last updated: 2016-04-22
Mirea, T., DeMiguel-Ramos, M., Clement, M., Olivares, J., Iborra, E., Yantchev, V. & Katardjiev, I. (2014). AlN Solidly Mounted Resonators for High Temperature Applications. In: 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS): . Paper presented at IEEE International Ultrasonics Symposium (IUS), SEP 03-06, 2014, Chicago, IL (pp. 1524-1527).
Open this publication in new window or tab >>AlN Solidly Mounted Resonators for High Temperature Applications
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2014 (English)In: 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS), 2014, p. 1524-1527Conference paper, Published paper (Refereed)
Abstract [en]

Monitoring under harsh environments, particularly high temperatures (> 600 degrees C), is on high demand nowadays. Applications such as gas control in propulsion systems or fire detection in early stages are good examples. During the last decades, materials and devices have been extensively investigated for these applications. Few have proven thermal and chemical stability. Among the most used devices are surface acoustic wave (SAW) resonators using a langasite (LGS) substrate. Their main disadvantage is related to their transducer topology. Their long and narrow electrode strips are subjected to destructive agglomeration. In order to solve this problem, solidly mounted bulk resonators (SMR) are here proposed as an alternative. They provide rigidity, high performance and large electrodes. Here we investigate the performance of SMR devices after annealing under vacuum condition at 700 degrees C for a cumulative time of 24h. SMRs are composed of porous-SiO2/Mo Bragg mirrors and Ir or Mo electrodes. Their performance shows and initial overall improvement with subsequent stabilization. Q(p)xk(eff)(2) in the order of 72 are achieved. Further investigations on full dielectric Bragg mirrors will be performed. With this initial study we demonstrate that SMRs can be a good alternative to SAWs for high temperature applications.

Keywords
Solidly Mounted Resonator, AlN, sensor, high temperature
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-257128 (URN)10.1109/ULTSYM.2014.0377 (DOI)000352792500376 ()978-1-4799-7049-0 (ISBN)
Conference
IEEE International Ultrasonics Symposium (IUS), SEP 03-06, 2014, Chicago, IL
Available from: 2015-06-30 Created: 2015-06-30 Last updated: 2016-04-22Bibliographically approved
Kubart, T., Moreira, M. & Katardjiev, I. (2014). Thin AlN films deposited by reactive HiPIMS and pulsed DC sputtering – a comparative study. In: 14th International Conference on Plasma Surface Engineering, September 15 - 19, 2014, Garmisch-Partenkirchen, Germany: . Paper presented at 14th International Conference on Plasma Surface Engineering, September 15 - 19, 2014, Garmisch-Partenkirchen, Germany.
Open this publication in new window or tab >>Thin AlN films deposited by reactive HiPIMS and pulsed DC sputtering – a comparative study
2014 (English)In: 14th International Conference on Plasma Surface Engineering, September 15 - 19, 2014, Garmisch-Partenkirchen, Germany, 2014Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

High quality wurtzite polycrystalline thin AlN films can be grown at low temperature by reactive magnetron sputtering provided sufficient energy input. Typically, a suitable substrate or a seed layer is used to improve the AlN crystallinity. In this study, thin films grown by pulsed DC (PDCS) and High Power Impulse Magnetron Sputtering (HiPIMS) from an Al target were studied aiming at both higher film quality as well as film deposition in cases where a seed layer is impractical. The deposition process was first characterized with respect to the Ar to N2 gas flow ratio. For selected process conditions, AlN films were prepared with a thickness of about 200 nm.  (100) Si and (110) Mo coated Si substrates were used and no intentional substrate heating was employed. The crystalline texture of the AlN films was determined with various XRD techniques.

Although the deposition rates with HiPIMS are generally lower than those with PDCS, the transition from metal to compound mode spans over a significantly larger range of N2 gas flow. Therefore, with HiPIMS it is possible to deposit stoichiometric AlN in the transition region at deposition rates comparable with PDCS. Owing to the increased energy input in the HiPIMS process, the film texture is improved which is especially pronounced at low film thicknesses.

Keywords
AlN, Thin films, HiPIMS
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:uu:diva-234702 (URN)
Conference
14th International Conference on Plasma Surface Engineering, September 15 - 19, 2014, Garmisch-Partenkirchen, Germany
Available from: 2014-10-23 Created: 2014-10-23 Last updated: 2016-04-22
Moreira, M., Bjurström, J., Katardjiev, I. & Yantchev, V. (2013). Efficient RF voltage transformer with bandpass filter characteristics. Electronics Letters, 49(3), 198-199
Open this publication in new window or tab >>Efficient RF voltage transformer with bandpass filter characteristics
2013 (English)In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 49, no 3, p. 198-199Article in journal (Refereed) Published
Abstract [en]

A microwave bandpassfilter with a large ratio between the output andthe input impedance has been designed and fabricated. Consequently,it functions both as a voltage transformer and a bandpassfilter, or trans-filter for brevity. It represents a two-port micro-acoustic resonatoremploying Lamb waves in a thin piezoelectric AlNfilm grown ontoa Si carrier substrate with a centre frequency of around 887 MHz.The transfilter has a transformer ratio of 10 and a voltage efficiencyof over 80%. The component has a small size ( < 0.5 mm2) and isshown to sustain power levels of 250 mW. It can be used in avariety of cases where both voltage amplification and frequencyfilter-ing are required. Examples include: charge pumps in RFID tags,energy scavenging, remotely triggered switches, wake-up radios inwireless networks, stand-by units in home electronics etc.

Place, publisher, year, edition, pages
iet, 2013
Keywords
wireless, Lamb wave, trasnformer, RF
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-185262 (URN)10.1049/el.2012.3982 (DOI)000318542500023 ()
Projects
WiSENET and VR granted "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications "
Funder
VinnovaSwedish Research Council, 2009-5056
Available from: 2012-11-21 Created: 2012-11-21 Last updated: 2017-12-07Bibliographically approved
Yantchev, V. & Katardjiev, I. (2013). Thin film lamb wave resonators in frequency control and sensing applications: a review. Journal of Micromechanics and Microengineering, 23(4), 043001
Open this publication in new window or tab >>Thin film lamb wave resonators in frequency control and sensing applications: a review
2013 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 4, p. 043001-Article in journal (Refereed) Published
Abstract [en]

This work makes an overview of the progress made during the last decade with regard to a novel class of piezoelectric microwave devices employing acoustic Lamb waves in micromachined thin film membranes. This class of devices is referred to as either thin film Lamb wave resonators or piezoelectric contour-mode resonators both employing thin film aluminum nitride membranes. These devices are of interest for applications in both frequency control and sensing. High quality factor Lamb wave resonators exhibiting low noise, low loss and thermally stable performance are demonstrated and their application in high resolution gravimetric and pressure sensors further discussed. A specific emphasis is put on the ability of these devices to operate in contact with liquids. Future research directions are further outlined.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2013
Keywords
MEMS, resonator, thin film, sensor, frequency
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-196353 (URN)10.1088/0960-1317/23/4/043001 (DOI)000316299900001 ()
Projects
VR granted "Thin Film Guided Microacoustic Waves in Periodical Systems: Theory and Applications "
Funder
Swedish Research Council, 2009-5056
Note

TOPICAL REVIEW

Available from: 2013-03-08 Created: 2013-03-08 Last updated: 2017-12-06Bibliographically approved
Katardjiev, I. & Yantchev, V. (2012). A Passive Radio Triggered Switch with ID Functionality. us PCT/US12/38176.
Open this publication in new window or tab >>A Passive Radio Triggered Switch with ID Functionality
2012 (English)Patent (Other (popular science, discussion, etc.))
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-189958 (URN)
Patent
US PCT/US12/38176
Projects
WISENET
Funder
VinnovaSwedish Research Council, 2009-5056
Available from: 2013-01-05 Created: 2013-01-05 Last updated: 2013-03-22Bibliographically approved
Yantchev, V. & Katardjiev, I. (2012). Advances in the Lamb wave resonator technology. In: International Symposium on Utrasonics, ferroelectrics and frequency control. Paper presented at International Symposium on Utrasonics, ferroelectrics and frequency control.
Open this publication in new window or tab >>Advances in the Lamb wave resonator technology
2012 (English)In: International Symposium on Utrasonics, ferroelectrics and frequency control, 2012Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-185255 (URN)
Conference
International Symposium on Utrasonics, ferroelectrics and frequency control
Funder
Swedish Research Council, 2009-5056
Available from: 2012-11-21 Created: 2012-11-21 Last updated: 2013-03-13
Arapan, L., Katardjiev, I. & Yantchev, V. (2012). An intermode-coupled thin-film micro-acoustic resonator. Journal of Micromechanics and Microengineering, 22(8), 085004
Open this publication in new window or tab >>An intermode-coupled thin-film micro-acoustic resonator
2012 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 8, p. 085004-Article in journal (Refereed) Published
Abstract [en]

A novel concept for the development of thin-film micro-acoustic resonators based on the coupling between different plate acoustic modes was demonstrated. The basic principles for the design and fabrication of intermode-coupled plate acoustic wave resonators on c-textured thin AlN films were presented and first experimental proof of coupling between laterally propagating waves and BAW was demonstrated. The experimental results demonstrate that the grating-assisted intermode coupling can be employed in high-frequency resonators inheriting the low dispersive nature of the S0 mode in combination with the energy localization in the plate bulk typical for the fundamental thickness shear resonance.

Keywords
acoustic resonator, aluminium nitride, Lamb wave, mode conversion
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics; Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-178590 (URN)10.1088/0960-1317/22/8/085004 (DOI)000306649000004 ()
Funder
Swedish Research Council, 2009-5056
Available from: 2012-08-01 Created: 2012-08-01 Last updated: 2017-12-07Bibliographically approved
Yantchev, V., Arapan, L., Ivanov, I., Uzunov, I., Katardjiev, I. & Plessky, V. (2012). Parametric Study of Thin-film Zero-Group Velocity Resonators. In: 2012 IEEE International Utrasonics Symposium (IUS): . Paper presented at IEEE International Ultrasonics Symposium, IUS, Oct 7-10, 2013, Dresden, Germany (pp. 307-310).
Open this publication in new window or tab >>Parametric Study of Thin-film Zero-Group Velocity Resonators
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2012 (English)In: 2012 IEEE International Utrasonics Symposium (IUS), 2012, p. 307-310Conference paper, Published paper (Refereed)
Abstract [en]

Here we demonstrate experimentally a novel, small form factor, resonant architecture employing the intrinsic zero-group-velocity dispersion of the first order symmetric Lamb wave S1 propagating in piezoelectric AlN film membranes. Designs with different topologies were fabricated and compared. FEM analysis is used to verify the observed differences while providing a deeper insight to the resonator performance. Technique for improvement of the device performance are further proposed.

Series
IEEE International Ultrasonics Symposium
Keywords
AlN; Lamb Wave; Resonator; Thin Film
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-185257 (URN)10.1109/ULTSYM.2012.0075 (DOI)000326960200067 ()978-146734561-3 (ISBN)
Conference
IEEE International Ultrasonics Symposium, IUS, Oct 7-10, 2013, Dresden, Germany
Funder
Swedish Research Council, 2009-5056
Available from: 2012-11-21 Created: 2012-11-21 Last updated: 2014-01-05Bibliographically approved
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