Silicon carbide X-ray beam position monitors for synchrotron applications

Nida, Selamnesh; Tsibizov, Alexander; Ziemann, Thomas; Woerle, Judith; Moesch, Andy; Schulze-Briese, Clemens; Pradervand, Claude; Tudisco, S.; Sigg, H.; Bunk, Oliver; Großner, Ulrike; Camarda, Massimo

doi:10.1107/s1600577518014248

Cited by 22 publications

(21 citation statements)

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“…Ions collectors allow to calculate the velocity distribution of charged particles escaped from the plasma. Recently has been implemented new solid state detectors base on Silicon Carbide material [10][11][12][13][14], which can be used as e plasma diagnostic and also as nuclear fragments detectors. Moreover, a Thomson Parabola Spectrometer (TPS) is employed to characterize ion beams.…”

Section: Visible Photons X-ray and Ionic Component Characterizationmentioning

confidence: 99%

LENS - Laser Energy for Nuclear Science facility @ LNS

et al. 2020

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Section: Visible Photons X-ray and Ionic Component Characterizationmentioning

confidence: 99%

LENS - Laser Energy for Nuclear Science facility @ LNS

et al. 2020

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“…The substrate removal was obtained by electrochemical etching. ECE is an oxidation/oxide-removal process obtained by dipping the SiC wafer in a hydrofluoridric acid-based solution and electrically supply holes for the oxidation through a 100 nm aluminium back metal contact [6,[21][22][23]. The process is capable of removing highly doped (≥ 10 18 cm −3 ) p-type and n-type layers but is selective towards low-doped n-type layers (selectivity > 1000:1 with respect to the 5 × 10 13 cm −3 doped n − layer).…”

Section: Sample Preparationmentioning

confidence: 99%

“…The realized membranes have thicknesses and uniformities determined by the epitaxial layer. The 4H-SiC suspended film with circular shape was fabricated at the Paul Scherrer Institute [6]. In addition, the circular shape is the most appropriate geometry in order to study the effects related to the internal stress of a film.…”

Section: Sample Preparationmentioning

confidence: 99%

“…Until now, very few papers deal with the fabrication of 4H-SiC MEMS structures. Thus, Nida et al proposed a promising technique employing a highly selective etching of 4H-SiC homoepitaxy films [6]. The etching process stops at the interface between n + 4H-SiC substrate and n − 4H-SiC epilayer, enabling the fabrication of freestanding thin films.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the crystalline quality of the epilayer, and so, the suspended thin-film, is not affected by the process [7]. This method could pave the road for the fabrication of novel SiC-based detectors [6]. However, designing such original film for MEMS applications requires knowing the mechanical properties of the epilayers.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Young’s Modulus and the Residual Stress of 4H-SiC Circular Membranes on 4H-SiC Substrates

et al. 2019

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The stress state is a crucial parameter for the design of innovative microelectromechanical systems based on silicon carbide (SiC) material. Hence, mechanical properties of such structures highly depend on the fabrication process. Despite significant progresses in thin-film growth and fabrication process, monitoring the strain of the suspended SiC thin-films is still challenging. However, 3C-SiC membranes on silicon (Si) substrates have been demonstrated, but due to the low quality of the SiC/Si heteroepitaxy, high levels of residual strains were always observed. In order to achieve promising self-standing films with low residual stress, an alternative micromachining technique based on electrochemical etching of high quality homoepitaxy 4H-SiC layers was evaluated. This work is dedicated to the determination of their mechanical properties and more specifically, to the characterization of a 4H-SiC freestanding film with a circular shape. An inverse problem method was implemented, where experimental results obtained from bulge test are fitted with theoretical static load-deflection curves of the stressed membrane. To assess data validity, the dynamic behavior of the membrane was also investigated: Experimentally, by means of laser Doppler vibrometry (LDV) and theoretically, by means of finite element computations. The two methods provided very similar results since one obtained a Young’s modulus of 410 GPa and a residual stress value of 41 MPa from bulge test against 400 GPa and 30 MPa for the LDV analysis. The determined Young’s modulus is in good agreement with literature values. Moreover, residual stress values demonstrate that the fabrication of low-stressed SiC films is achievable thanks to the micromachining process developed.

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Ultra‐high dose rate dosimetry: Challenges and opportunities for FLASH radiation therapy

et al. 2022

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The clinical translation of FLASH radiotherapy (RT) requires challenges related to dosimetry and beam monitoring of ultra‐high dose rate (UHDR) beams to be addressed. Detectors currently in use suffer from saturation effects under UHDR regimes, requiring the introduction of correction factors. There is significant interest from the scientific community to identify the most reliable solutions and suitable experimental approaches for UHDR dosimetry. This interest is manifested through the increasing number of national and international projects recently proposed concerning UHDR dosimetry. Attaining the desired solutions and approaches requires further optimization of already established technologies as well as the investigation of novel radiation detection and dosimetry methods. New knowledge will also emerge to fill the gap in terms of validated protocols, assessing new dosimetric procedures and standardized methods. In this paper, we discuss the main challenges coming from the peculiar beam parameters characterizing UHDR beams for FLASH RT. These challenges vary considerably depending on the accelerator type and technique used to produce the relevant UHDR radiation environment. We also introduce some general considerations on how the different time structure in the production of the radiation beams, as well as the dose and dose‐rate per pulse, can affect the detector response. Finally, we discuss the requirements that must characterize any proposed dosimeters for use in UDHR radiation environments. A detailed status of the current technology is provided, with the aim of discussing the detector features and their performance characteristics and/or limitations in UHDR regimes. We report on further developments for established detectors and novel approaches currently under investigation with a view to predict future directions in terms of dosimetry approaches, practical procedures, and protocols. Due to several on‐going detector and dosimetry developments associated with UHDR radiation environment for FLASH RT it is not possible to provide a simple list of recommendations for the most suitable detectors for FLASH RT dosimetry. However, this article does provide the reader with a detailed description of the most up‐to‐date dosimetric approaches, and describes the behavior of the detectors operated under UHDR irradiation conditions and offers expert discussion on the current challenges which we believe are important and still need to be addressed in the clinical translation of FLASH RT.

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Silicon carbide X-ray beam position monitors for synchrotron applications

Abstract: The viability of thin 4H-SiC membrane X-ray beam position monitors in synchrotrons is investigated. Devices are fabricated and show improved linearity, dynamics and signal-to-noise ratio compared with commercial polycrystalline diamond X-ray beam position monitors.

Cited by 22 publications

References 21 publications

LENS - Laser Energy for Nuclear Science facility @ LNS

LENS - Laser Energy for Nuclear Science facility @ LNS

Investigation of the Young’s Modulus and the Residual Stress of 4H-SiC Circular Membranes on 4H-SiC Substrates

Ultra‐high dose rate dosimetry: Challenges and opportunities for FLASH radiation therapy

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