abstract

while polycrystalline lead oxide (poly-pbo) is known to be one of the most promising photoconductors for utilization in x-ray detectors, its major performance parameters such as charge yield and mobility-lifetime product (μτ) are still not well established and require further investigation. combining the conventional x-ray induced photocurrent and pulse height spectroscopy techniques we examine the x-ray photogeneration and recombination processes in poly-pbo. the measurements indicate that the amount of energy required to release a single electron-hole pair w± (inverse of charge yield) strongly depends on the applied electric field and at 10 v/μm reaches ~20 ev/ehp. fitting the measured pulse height spectra with the hecht formula provided μτ for holes and electrons to be 4.1 × 10−8 cm²/v and 10−9 cm²/v, respectively. obtained μτ values combined with recently reported mobility values of charge carriers in pbo suggest a new direction towards an improvement of pbo technology by incorporation of frisch grid or x-ray transistor architectures.

continue reading the article: https://www.nature.com/articles/s41598-017-09168-3

the post congratulations to oleksii semeniuk on publishing a paper in nature scientific reports appeared first on rezniklab and posted by pavlo karasyuk.

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abstract

lead oxide (pbo) is one of the most promising materials for application in direct conversion medical imaging x-ray detectors. despite its high potential, conventional polycrystalline pbo layers deposited with the basic thermal evaporation method are not yet mature for practical use in x-ray imaging; indeed, they are highly porous, unstable at ambient conditions, and substoichiometric. in order to combat the above issues with pbo, we advance the basic evaporation process with simultaneous energetic ion bombardment of the growing film. we show that tuning the ion-assisted thermal deposition not only solves the structural problems of poly-pbo, but also enables the growth of a new noncrystalline polymorphic form of the material—amorphous pbo (a-pbo). in contrast to poly-pbo, novel a-pbo layers grown by ion-assisted thermal deposition are stable at ambient conditions. structural and morphological analysis confirms that a-pbo is stoichiometric and free of detectable voids, which suggests higher bulk x-ray stopping power than porous poly-pbo.

continue reading the article: https://link.springer.com/article/10.1007%2fs10853-017-0998-5

the post congratulations to oleksii semeniuk on publishing a paper in journal of materials science appeared first on rezniklab and posted by pavlo karasyuk.