Large single‐crystal diamond substrates for ionizing radiation detection

Girolami, M.; Bellucci, A.; Calvani, P.; Trucchi, Daniele M.

doi:10.1002/pssa.201600262

Cited by 12 publications

(8 citation statements)

References 32 publications

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“…Careful chemical selection of the polymer-dopant combination, and optimisation of the dopant concentration, permits the benchmark mobility-lifetime (µτ) product to be sensitively controlled for the majority electronic carrier according to the target application. The µτ product has historically been recognized as a significant controlling parameter for the achievable efficiency of thin-film inorganic solar cells [1,2], and more recently in the development of optimized thin-film organic solar cells [3] and large-volume crystalline detectors for ionizing radiation [4]. The long-term stability of such µτ magnitudes in MDPs may be seriously compromised, however, via unwanted internal chemical reactions.…”

Section: Introductionmentioning

confidence: 99%

An Evaluation of Optical Absorbance Kinetics for the Detection of Micro-Porosity in Molecularly Doped Polymer Thin-Films

Goldie

Skelton

Bailey

2021

Solids

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The use of optical absorbance kinetics to identify micro-porous regions in doped polymer films is evaluated. Data are presented for a series of hydrazone doped polymer films which are found to optically bleach upon exposure to an ultra violet (UV) radiation source. The UV absorbance kinetics are found to exhibit distinctive characteristics for the various polymers studied, with changes in film absorbance occurring either in a fast (<103 s) or slow (>104 s) timescale. An interpretation of these distinctive timescales based upon a cellular-automata model of the absorbance kinetics suggests that the underlying photo-oxidation of the hydrazone is highly sensitive to underlying micro-porosity in the films which controls the necessary supply of absorbed oxygen for photo-cyclic reaction.

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Section: Introductionmentioning

confidence: 99%

An Evaluation of Optical Absorbance Kinetics for the Detection of Micro-Porosity in Molecularly Doped Polymer Thin-Films

Goldie

Skelton

Bailey

2021

Solids

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“…Furthermore, fabrication of diamond detectors is expensive due to the low yield of production and response reproducibility. Single-crystal diamond substrates are limited to lateral dimensions less than 9x9 mm 2 , leading to expensive mosaic detectors that limit their compatibility with scaled-up fabrication processes 10,11 . The PTW microDiamond is currently the only commercial diamond based detector being considered for a range of radiation therapy applications due to its high spatial resolution (1 μm thick sensitive volume 12 ) when operated in edge-on mode 13 and capability to perform dosimetry in real time 14 .…”

Section: Introductionmentioning

confidence: 99%

“…Single-crystal diamond substrates are limited to lateral dimensions <999 mm 2 , leading to expensive mosaic detectors that limit their compatibility with scaled-up fabrication processes. 10,11 The PTW microDiamond is currently the only commercial diamond-based detector being considered for a range of radiation therapy applications due to its high spatial resolution (1-lm-thick sensitive volume 12 ) when operated in edge-on mode 13 and capability to perform dosimetry in real time. 14 However, in small field dosimetry, the PTW microDiamond over responds in fields smaller than 20mm compared to other detectors due to the perturbation created by extra cameral materials such as the electrodes.…”

Section: Introductionmentioning

confidence: 99%

Characterization of an organic semiconductor diode for dosimetry in radiotherapy

et al. 2020

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The development of novel detectors for dosimetry in advanced radiotherapy modalities requires materials that have a water-equivalent response to ionizing radiation such that characterization of radiation beams can be performed without the need for complex calibration procedures and correction factors. Organic semiconductors are potentially an ideal technology in fabricating devices for dosimetry due to tissue-equivalence, mechanical flexibility and relatively cheap manufacturing cost. The response of a commercial organic photodetector (OPD), coupled to a plastic scintillator, to ionizing radiation from a linear accelerator and orthovoltage x-ray tube has been characterized to assess its potential as a dosimeter for radiotherapy. The radiation hardness of the OPD has also been investigated to demonstrate its longevity for such applications.Methods: Radiation hardness measurements were achieved by observing the response of the OPD to the visible spectrum and 70 keV x-rays after pre-exposure to 40 kGy of ionizing radiation. The response of a pre-irradiated OPD to 6 MV photons from a linear accelerator in reference conditions was compared to a non-irradiated OPD with respect to direct and indirect (RP400 plastic scintillator) detection mechanisms. Dose-rate dependence of the OPD was measured by varying the surface-to-source distance between 90 cm and 300 cm. Energy dependence was characterized from 29.5 keV to 129 2 keV with an x-ray tube. The percentage depth dose (PDD) curves were measured from 0.5 cm to 20 cm and compared to an ionization chamber. Results:The OPD sensitivity to visible light showed substantial degradation of the broad 450nm to 600 nm peak from the donor after irradiation to 40 kGy. After irradiation, the spectral shape has a dominant absorbance peak at 370 nm, as the acceptor better withstood radiation damage. Its response to x-rays stabilized to 30% after 35 kGy, with a 0.5% difference between 770 Gy increments. The OPD exhibited reproducible detection of ionizing radiation when coupled with a scintillator. Indirect detection showed a linear response from 25 cGy to 500 cGy and constant response to dose-rates from 0.31 Gy/pulse to 3.4 x10 -4 Gy/pulse. However, without the scintillator, response increased by 100% at low dose rates.Energy independence between 100 keV and 1.2 MeV advocates their use as a dosimeter without beam correction factors.A dependence on the scintillator thickness used during a comparison of the PDD to the ionizing chamber was identified.A 1 mm thick scintillator coupled with the OPD demonstrated the best agreement of ±3%. Conclusions:The response of OPDs to ionizing radiation has been characterized, showing promising use as a dosimeter when coupled with a plastic scintillator. The mechanisms of charge transport and trapping within organic materials varies for visible and ionizing radiation, due to differing properties for direct and indirect detection mechanisms and observing a substantial decrease of sensitivity to the visible spectrum after 40 kGy. This study proved that OP...

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“…Due to their high atomic density, strong bonding, and crystal structure of high symmetry, diamonds show high Raman gain coefficient, which makes them suitable for high power diamond Raman lasers [6]. With a wide bandgap of 5.5 eV, a high breakdown field, high carrier mobility, and high radiation hardness, diamonds are an ideal material for high energy particle and ionizing radiation detection [7][8][9][10]. Furthermore, diamonds exhibit exceptional electronic properties, such as a high breakdown field (>10 MV/cm) and high carrier mobility (4500 cm 2 /Vs for electrons and 3800 cm 2 /V for holes), which makes diamond an excellent candidate for next generation semiconductor materials [11,12].…”

Section: Introductionmentioning

confidence: 99%

Single Crystal Diamond Deposited by Dual Radio-Frequency Plasma Jet CVD with High Growth Rate

Líu

et al. 2019

Crystals

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Single crystal diamonds were deposited on high pressure high temperature (HPHT) substrate with high growth rate, up to 18.5 μm/h, by using dual radio-frequency inductive coupled plasma jet. The methane flux was found to influence the growth rate of single crystal diamond. The reason for this might be ascribed to the electron temperature increase, raising the flux of methane, based on the plasma diagnosis results by optical emission spectra (OES). The results of Raman spectroscopy and the X-ray rocking-curve indicated that as-deposited diamonds are of good quality.

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Large single‐crystal diamond substrates for ionizing radiation detection

Cited by 12 publications

References 32 publications

An Evaluation of Optical Absorbance Kinetics for the Detection of Micro-Porosity in Molecularly Doped Polymer Thin-Films

An Evaluation of Optical Absorbance Kinetics for the Detection of Micro-Porosity in Molecularly Doped Polymer Thin-Films

Characterization of an organic semiconductor diode for dosimetry in radiotherapy

Single Crystal Diamond Deposited by Dual Radio-Frequency Plasma Jet CVD with High Growth Rate

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