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Electrical characterization of wurtzite (Al,B)N thin films
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
2011 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 4, 466-470 p.Article in journal (Refereed) Published
Abstract [en]

Wurtzite aluminum nitride (w-AlN) thin films are of great interest for electro-acoustic applications and their material properties have in recent years been extensively studied. One way to tailor material properties is to vary the composition by adding other elements. Boron is an element that can take the place of aluminum in the crystal lattice of w-AlN. In the present study, polycrystalline w-(AI,B)N thin films were grown on p-Si(100) and Al/p-Si(100) substrates by pulsed DC reactive magnetron sputtering from a single Al/B target. MIS and MIM structures were fabricated to investigate the electrical properties of w-(AI,B)N thin films. Important dielectric thin film properties for microelectronics applications are the breakdown field, the permittivity (K) and leakage current through the film. The (AI,B)N thin film is found to have a dielectric strength of similar to 3 x 10(6) V cm(-1) and a kappa close to 12. The measured leakage current through the film is assumed to be mainly due to Frenkel-Poole emission with a trap energy at 0.71 eV below the conduction band edge.

Place, publisher, year, edition, pages
Elsevier , 2011. Vol. 86, no 4, 466-470 p.
Keyword [en]
w-AlBN, Reactive sputtering, Permittivity, Breakdown field, Leakage current
National Category
Natural Sciences Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-161821DOI: 10.1016/j.vacuum.2011.10.002ISI: 000298212000021OAI: oai:DiVA.org:uu-161821DiVA: diva2:457541
Available from: 2011-11-18 Created: 2011-11-18 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Reactive Sputter Deposition of Functional Thin Films
Open this publication in new window or tab >>Reactive Sputter Deposition of Functional Thin Films
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Thin film technology is of great significance for a variety of products, such as electronics, anti-reflective or hard coatings, sensors, solar cells, etc. This thesis concerns the synthesis of thin functional films, reactive magnetron sputter deposition process as such and the physical and functional characterization of the thin films synthesized. Characteristic for reactive sputtering processes is the hysteresis due to the target poisoning. One particular finding in this work is the elimination of the hysteresis by means of a mixed nitrogen/oxygen processing environment for dual sputtering of Alumina-Zirconia thin films. For a constant moderate flow of nitrogen, the hysteresis could be eliminated without significant incorporation of nitrogen in the films. It is concluded that optimum processing conditions for films of a desired composition can readily be estimated by modeling. The work on reactively sputtered SiO2–TiO2 thin films provides guidelines as to the choice of process parameters in view of the application in mind, by demonstrating that it is possible to tune the refractive index by using single composite Six/TiO2 targets with the right composition and operating in a suitable oxygen flow range. The influence of the target composition on the sputter yield is studied for reactively sputtered titanium oxide films. It is shown that by using sub-stoichiometric targets with the right composition and operating in the proper oxygen flow range, it is possible to increase the sputter rate and still obtain stoichiometric coatings. Wurtzite aluminum nitride (w-AlN) thin films are of great interest for electro-acoustic applications and their properties have in recent years been extensively studied. One way to tailor material properties is to vary the composition by adding other elements. Within this thesis (Al,B)N films of the wurtzite structure and a strong c-axis texture have been grown by reactive sputter deposition. Nanoindentation experiments show that the films have nanoindentation hardness in excess of 30 GPa, which is as hard as commercially available hard coatings such as TiN. Electrical properties of w-(Al,B)N thin films were investigated. W-(Al,B)N thin films are found to have a dielectric strength of ~3×106 V/cm, a relatively high k-value around 12 and conduction mechanisms similar to those of AlN. These results serve as basis for further research and applications of w-(Al,B)N thin films. An AlN thin film bulk acoustic resonator (FBAR) and a solidly mounted resonator (SMR) together with a microfluidic transport system have been fabricated. The fabrication process is IC compatible and uses reactive sputtering to deposit piezoelectric AlN thin films with a non-zero mean inclination of the c-axis, which allows in-liquid operation through the excitation of the shear mode. The results on IC-compatibility, Q-values, operation frequency and resolution illustrate the potential of this technology for highly sensitive low-cost micro-biosensor systems for applications in, e.g. point-of-care testing.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 52 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 945
Keyword
thin film, reactive sputtering, coating, resonator, sensor, FBAR, SMR, aluminum nitride, (Al, B)N
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-175666 (URN)978-91-554-8403-3 (ISBN)
Public defence
2012-09-21, Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2012-08-17 Created: 2012-06-11 Last updated: 2013-01-22

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Liljeholm, LinaOlsson, Jörgen

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