Fabrication of a Hydrogenated Amorphous Silicon Detector in 3-D Geometry and Preliminary Test on Planar Prototypes

Menichelli, M.; Bizzarri, M.; Boscardin, M.; Caprai, M.; Caricato, Anna Paola; Cirrone, Giuseppe Antonio Pablo; Crivellari, M.; Cupparo, Ilaria; Cuttone, G.; Dunand, S.; Fanò, L.; Ali, O. Hammad; Ionica, M.; Kanxheri, K.; Large, Matthew J.; Maruccio, Giuseppe; Monteduro, Anna Grazia; Moscatelli, F.; Morozzi, A.; Papi, A.; Passeri, D.; Petasecca, Marco; Rizzato, Silvia; Rossi, Alessandro; Scorzoni, A.; Servoli, L.; Talamonti, Cinzia; Verzellesi, Giovanni; Wyrsch, Nicolas

doi:10.3390/instruments5040032

Cited by 12 publications

(11 citation statements)

References 26 publications

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“…An advantageous feature of a-Si:H is its superior radiation hardness, with Wyrsch et al (2006) reporting an increase in the leakage current of a 32.6 μm a-Si:H p-i-n diode of only a factor of 2 when held at a 9 × 10 4 V cm −1 electric field and irradiated with 24 GeV protons up to a fluence of 7 × 10 15 p cm −2 . Furthermore, the radiation hardness and sensitivity of a-Si:H devices exposed to gamma irradiation has been reported (Boudry and Antonuk 1994, Kim et al 2002, Menichelli et al 2021. Detailed motivations behind the use of a-Si:H diodes for beam monitoring and dosimetry in high-dose environments is presented in full in Menichelli et al (2020).…”

Section: Introductionmentioning

confidence: 99%

Hydrogenated amorphous silicon high flux x-ray detectors for synchrotron microbeam radiation therapy

Large,

Bizzarri,

Calcagnile

et al. 2023

Phys. Med. Biol.

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Objective: Microbeam radiation therapy (MRT) is an alternative emerging radiotherapy treatment modality which has demonstrated effective radioresistant tumour control while sparing surrounding healthy tissue in preclinical trials. This apparent selectivity is achieved through MRT combining ultra-high dose rates with micron-scale spatial fractionation of the delivered X-ray treatment field. Quality assurance dosimetry for MRT must therefore overcome a significant challenge, as detectors require both a high dynamic range and a high spatial resolution to perform accurately. Approach: In this work, a series of radiation hard a-Si:H diodes, with different thicknesses and carrier selective contact configurations, have been characterized for X-ray dosimetry and real-time beam monitoring applications in extremely high flux beamlines utilised for MRT at the Australian Synchrotron. Results: These devices displayed superior radiation hardness under constant high dose-rate irradiations on the order of 6000 Gy/s, with a variation in response of 10% over a delivered dose range of approximately 600 kGy. Dose linearity of each detector to X-rays with a peak energy of 117 keV is reported, with sensitivities ranging from (2.74 ± 0.02) nC/Gy to (4.96 ± 0.02) nC/Gy. For detectors with 0.8 µm thick active a-Si:H layer, their operation in an edge-on orientation allows for the reconstruction of micron-size beam profiles (microbeams). The microbeams, with a nominal full-width-half-max of 50 µm and a peak-to-peak separation of 400 µm, were reconstructed with extreme accuracy. The full-width-half-max was observed as 55 ± 1 µm. Evaluation of the peak-to-valley dose ratio and dose-rate dependence of the devices, as well as an X-ray induced charge (XBIC) map of a single pixel is also reported. Significance: These devices based on novel a-Si:H technology possess a unique combination of accurate dosimetric performance and radiation resistance, making them an ideal candidate for X-ray dosimetry in high dose-rate environments such as FLASH and MRT. 

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Section: Introductionmentioning

confidence: 99%

Hydrogenated amorphous silicon high flux x-ray detectors for synchrotron microbeam radiation therapy

Large,

Bizzarri,

Calcagnile

et al. 2023

Phys. Med. Biol.

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“…Compared to crystalline silicon, where 3D detectors have a p-n structure, a-Si:H detectors in this geometry have to be designed as a p-i-n structure (for the reasons described in the previous section). For this purpose, the 3D-SiAm group-which is a collaboration between several INFN units (Italy), EPFL (CH), and University of Wollongong (Australia)is designing a detector like the one shown in Figure 4, where the inter-electrode distance is about 30 µm and the thickness of the detector is in the order of 100 µm [5,26,27]. This detector works as follows.…”

Section: D A-si:h Particle Detectorsmentioning

confidence: 99%

“…A nonexhaustive list of materials where a-Si:H can be deposited can be found in Ref. [5]. Detector-grade a-Si:H can be deposited with various techniques, such as PECVD with plasma excitation at radio frequency (13.56 MHz) [6], at very high frequency (VHF; 27-150 MHz) [7] or at microwave frequencies [8], and the wellestablished hot-wire chemical vapor deposition (HWCVD) [9].…”

Section: Introductionmentioning

confidence: 99%

“…Detector-grade a-Si:H can be deposited with various techniques, such as PECVD with plasma excitation at radio frequency (13.56 MHz) [6], at very high frequency (VHF; 27-150 MHz) [7] or at microwave frequencies [8], and the wellestablished hot-wire chemical vapor deposition (HWCVD) [9]. A recent effort is ongoing to deposit a-Si:H using pulsed laser deposition (PLD) [5].…”

Section: Introductionmentioning

confidence: 99%

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Status and perspectives of hydrogenated amorphous silicon detectors for MIP detection and beam flux measurements

2022

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Hydrogenated amorphous silicon (a-Si:H) particle detectors have been considered as alternatives to crystalline silicon detectors (c-Si) in high radiation environments, due to their excellent radiation hardness. However, although their capability for particle flux measurement in beam monitoring applications is quite satisfactory, their minimum ionizing particle (MIP) detection has always been problematic because of the poor signal-to-noise ratio caused by a low charge collection efficiency and relatively high (compared to crystalline silicon) leakage current. In this article, after a review of the status of technological research for a-Si:H detectors, a perspective view on MIP detection and beam flux measurements with these detectors will be given.

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“…A possible solution for these problems is a 3D detector geometry that allows to keep a relatively small inter-electrode distance (in the order of 25-30 µm) with detector thickness around 100 µm in order to increase the total charge generated in the detector by a MIP. The reduction of the distance between the electrodes is a crucial factor for keeping the leakage current low reducing the noise [5,6,7].…”

Section: Introductionmentioning

confidence: 99%

Displacement damage in Hydrogenated Amorphous Silicon p-i-n diodes and charge selective contacts detectors.

Menichelli¹,

Bizzarri²,

Boscardin³

et al. 2022

Preprint

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Hydrogenated amorphous silicon is a well known detector material for its radiation resistance. This study concern 10 µm thickness, p-i-n and charge selective contacts planar diode detectors which were irradiated with neutrons at two fluence values: 1016 neq/cm2 and 5 x 1016 neq/cm2. In order to evaluate their radiation resistance, detector leakage current and response to X-ray photons have been measured. The effect of annealing for performance recovery at 100°C for 12 and 24 hours has also been studied. The results for the 1016 neq/cm2 irradiation show a factor 2 increase in leakage current that is completely recovered after annealing for p-i-n devices while charge selective contacts devices show an overall decrease of the leakage current at the end of the annealing process compared to the measurement before the irradiation. X-ray dosimetric sensitivity degrades, for this fluence, at the end of irradiation but partially recovers for charge selective contacts devices and increases for p-i-n devices at the end of the annealing process. Concerning the 5 x 1016 neq/cm2 irradiation test (for p-i-n structures only), due to the activation occurred during the irradiation phase, the results were taken after 146 days of storage around 0° C when a self-annealing effect may have occurred. Nevertheless the results shows a degradation in leakage current and x-ray sensitivity which changes very little after annealing.

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Fabrication of a Hydrogenated Amorphous Silicon Detector in 3-D Geometry and Preliminary Test on Planar Prototypes

Cited by 12 publications

References 26 publications

Hydrogenated amorphous silicon high flux x-ray detectors for synchrotron microbeam radiation therapy

Hydrogenated amorphous silicon high flux x-ray detectors for synchrotron microbeam radiation therapy

Status and perspectives of hydrogenated amorphous silicon detectors for MIP detection and beam flux measurements

Displacement damage in Hydrogenated Amorphous Silicon p-i-n diodes and charge selective contacts detectors.

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