Improving Amorphous Selenium Photodetector Performance Using an Organic Semiconductor


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In this paper, a thin layer of perylene tetracarboxylic bisbenzimidazole (PTCBI) is investigated as a potential hole-blocking contact in an a-Se photodetector. The behavior of the device was characterized as a function of electric field under light and dark conditions. It was found that the PTCBI layer permits operation at high electric fields (>>10 V/μm) while maintaining a dark current density below 200 pA/mm2. Short pulse experiments were performed to assure that charge accumulation at the organic/a-Se interface is negligible and does not reduce the electric field in the a-Se layer. The detector investigated uses a simple low temperature fabrication process based on widely available semiconductor materials that can be easily integrated into current large area digital imager manufacturing processes.



Edited by:

Evangelos Hristoforou and Dr. Dimitros S. Vlachos




S. Abbaszadeh et al., "Improving Amorphous Selenium Photodetector Performance Using an Organic Semiconductor", Key Engineering Materials, Vol. 543, pp. 451-454, 2013

Online since:

March 2013




[1] S. O. Kasap, J. B. Frey, G. Belev, O. Tousignant, H. Mani, L. Laoerriere, A. Reznik, and J. A. Rowlands, Amorphous selenium and its alloys from early xeroradiography to high resolution X-ray image detectors and ultrasensitive imaging tubes, Phys. Stat. Sol. (b), vol. 246, no. 8, (2009).


[2] A. Reznik, W. Zhao, Y. Ohkawa, K. Tanioka, and J. A. Rowlands, Application of avalanche multiplication in amorphous selenium to flat panel detectors for medical applications, J. Matter Sci: Mater. Electron., vol. 20, no. 1, (2009), p. S63-S67.


[3] S. O. Kasap, M. Z. Kabir and J. A. Rowlands, Recent advances in X-ray photoconductors for direct conversion X-ray image detectors, Curr. Appl. Phys., vol. 6, no. 3, (2006), p.288–292.


[4] B. T. Polischuk, et al., Direct conversion digital X-ray detector with inherent high voltage protection for static and dynamic imaging, U. S. Patent 6 353 229, (2002).

[5] L. Cheung, et al., Amorphous selenium flat panel x-ray imager for tomosynthesis and static imaging, U. S. Patent 7 303 308, (2007).

[6] W. Zhao, D. Li, A. Reznik, B. J. M. Lui, D. C. Hunt, J. A. Rowlands, Y. Ohkawa, and K. Tanioka, Indirect flat-panel detector with avalanche gain: Fundumental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix fat panel imager), Med. Phys. Vol. 32, (2005).


[7] K. Tanioka et al., Avalanche-mode amorphous selenium photoconductive target for camera tube, Advance in electronics and electron physics, vol. 74, (1988), pp.379-386.

[8] K. Kikuchi, Y. Ohkawa, K. Miyakawa, T. Matsubara, K. Tanioka, M. Kubota, and N. Egami, Hole-blocking mechanism in high-gain avalanche rushing amorphous photoconductor (HARP) film, Phys. Status Solidi C, vol. 8, no. 9, (2011), pp.2800-2803.


[9] F. Nariyuki, S. Imai, H. Watano, T. Nabeta, and Y. Hosoi, New development of large-area direct conversion detector for digital radiography using amorphous selenium with C60-doped polymer layer, Proc. SPIE, vol. 7622, (2010), p.762240.


[10] I. H. Campbell, Improving the spectral response of amorphous selenium Se photodetector using organic semiconductors, Appl. Phys. Lett., vol. 99, (2011), p.063303.


[11] W. Que, and J. A. Rowlands, X-ray photogeneration in amorphous selenium: Geminate versus columnar recombination, Phys. Rev. B, vol. 51, no. 16, (1995), p.10500–10507.


[12] D. M. Pai and R. C. Enck, Onsager mechanism of photogeneration in amorphous selenium, Phys. Rev. B, vol. 11, no. 12, (1975), p.5163–5174.


[13] M. M. Wronski, et al., A solid-state amorphous selenium avalanche technology for low photon flux imaging application, Med. Phys., vol. 37, no. 9, (2010), pp.4982-4985.


[14] R. E. Johanson, S. O. Kasap, J. Rowlands, and B. Polischuk, Metallic electrical contacts to stabilized amorphous selenium for use in X-ray imaging detectors, J. Non-Cryst. Solids, vol. 227-230, no. 2, (1998), p.1359–1362.


[15] S. A. Mahmood, M. Z. Kabir, O. Tousignant, H. Mani, J. Greenspan, and P. Botka, Dark current in multilayer amorphous selenium x-ray imaging detectors, Appl. Phys. Lett., vol. 92, (2008), p.223506.


[16] S. Abbaszadeh, K. Rom, O. Bubon, B. A. Weinstein, K. S. Karim, J. A. Rowlands, and A. Reznik, Effect of the substrate on transient photodarkening in stabilized amorphous selenium, J. Non-Cryst. Solids, in press.