Abstract
Vacuum flat panel detectors (VFPDs) using cold cathode have important applications in large-area photoelectric detection. Based on the electron-bombardment-induced photoconductivity (EBIPC) mechanism, the photoconductor-type VFPDs achieved high detection sensitivity. However, pixelated imaging devices have not yet been developed. In this paper, we fabricate a 4 × 7 pixel vacuum flat panel detector array made of ZnS photoconductor and ZnO nanowires cold cathode for an imaging application. The responsivity of the device and the pixel current uniformity are studied, and imaging of the patterned objects is achieved. Our results verify the feasibility of VFPDs for imaging.
Highlights
For the indirect conversion X-ray detectors, the incident X-rays are first converted into visible light by the scintillator, and the visible light is converted into electron-hole pairs (EHPs) by the photoconductor or photodiode [18,19]
The majority of commercial large-area X-ray detectors are based on indirect conversion detectors, which use a photoconductor or photodiode integrated with thin-film transistor (TFT) arrays [20], or a complementary metal-oxide-semiconductor (CMOS) to read out the photoelectric signal and realize imaging [21]
Nanomaterials 2022, 12, 884 vacuum photodetectors includes a photoconductor anode and a cold cathode field emitter array (FEA), which can be made into a large-area flat panel detector
Summary
X-ray imaging is widely used in industrial inspection [1], security screening [2], medical diagnosis, [3,4] etc. Nanomaterials 2022, 12, 884 vacuum photodetectors includes a photoconductor anode and a cold cathode field emitter array (FEA), which can be made into a large-area flat panel detector. Zhang et al reported vacuum flat panel detectors using ZnS photoconductor based on the electron-bombardment-induced photoconductivity (EBIPC) mechanism for possible high-sensitivity X-ray detection application [29]. The EBIPC mechanism indicates that light excitation acts as a trigger and generates initial EHPs, and electron beam bombardment causes an iterative multiplication of carriers They reported a sensitive direct conversion X-ray detector formed by ZnO nanowire field emitters and β-Ga2 O3 photoconductor target with the EBIPC mechanism, which can achieve a high internal gain (2.9 × ) and high detection sensitivity (3.0 × μCGy−1 air cm−2 ) for a 6 keV X-ray at the electric field of 22.5 V μm−1 [31,32]. We use the detector to eventually achieve imaging of the objects
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