Dark current suppression of amorphous selenium based photosensors by the ZnO hole blocking layer

Tung Yuan Yu, Fu-Ming Pan*, Cheng Yi Chang, Tien Hu, Jenn-Fang Chen, Jia Feng Wang, Cheng Lu Lin, Tsung Han Chen, Te Ming Chen

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

To study the influence of defects in the hole blocking layer (HBL) on the dark current of amorphous selenium (a-Se) based photosensors, we prepared ZnO thin films by reactive sputter deposition (RSD) for the use as the HBL of the photosensors. The ZnO HBL layers prepared with different oxygen flow rates were characterized by X-ray photoelectron spectroscopy, Raman scattering analysis and photoluminescence, indicating that the density of oxygen vacancies in the ZnO thin films is significantly affected by the oxygen flow rate. The deep level transient spectroscopy measurement reveals two hole trap levels present in the RSD deposited ZnO thin films; one is at 0.94 eV and the other at 0.24 eV above the valence band edge. The electrical performance of the a-Se photosensor is largely influenced by the amount of oxygen vacancies in the ZnO thin film. The a-Se photosensor with the ZnO HBL of the most oxygen vacancies has the lowest dark current and demonstrates the highest breakdown field.

Original languageEnglish
Pages (from-to)659-664
Number of pages6
JournalCurrent Applied Physics
Volume14
Issue number5
DOIs
StatePublished - 1 Jan 2014

Keywords

  • Amorphous Se
  • DLTS
  • Hole blocking layer
  • Oxygen vacancy
  • Zinc oxide

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