PROJECT TITLE :
Investigation of Hole-Blocking Contacts for High-Conversion-Gain Amorphous Selenium Detectors for X-Ray Imaging
In this paper, we investigated different organic and inorganic hole-blocking contacts for amorphous selenium (a-Se)-primarily based photodetectors: $hboxCeO_2$, $hboxTiO_2$, perylene tetracarboxylic bisbenzimidazole (PTCBI), and polyimide (PI). $hboxCeO_2$ has previously been used as a blocking layer for prime-gain a-Se devices. $hboxTiO_2$ has similar properties to $hboxCeO_2$. PTCBI features a higher ionization potential compared to a-Se and includes a terribly low hole mobility. PI is a common insulator in the semiconductor trade. It was found that an 800-nm PI layer reduces the dark current by additional than two orders of magnitude in comparison with 30 nm of $hboxCeO_2$, twenty nm of $hboxTiO_2$, and 50 nm of PTCBI. No significant charge trapping was found in the devices consisting of an 80zero-nm PI layer. Not like previously reported inorganic hole-blocking contact technology, PI layers further benefit from a simple spin coating fabrication step before evaporation of a-Se. Photodetector samples incorporating the PI layer are tested at high electrical fields, and gains reaching 4.four were observed at an electric field $>hbox80 hboxV/mu hboxm$. We tend to conclude that employing a PI layer could be a promising step in the development of high-conversion-gain detectors for rising applications in giant-area medical diagnostic imaging, crystallography, and nondestructive take a look at.
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