Evidence for band-to-band impact ionization in evaporated ZnS:Mn alternating-current thin-film electroluminescent devices

W. M. Ang, S. Pennathur, L. Pham, J. F. Wager, S. M. Goodnick, A. A. Douglas

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Abstract

Evidence is presented that the normal operation of evaporated ZnS:Mn alternating-current thin-film electroluminescent (ACTFEL) devices involves electron-hole pair generation by band-to-band impact ionization. Four observations are offered to support this assertion. These observations involve: (i) empirical field-clamping trends, (ii) experimental and simulated trends in charge transfer characteristics, (iii) experimental attempts to assess the interface distribution using a field-control circuit, and (iv) Monte Carlo simulation trends. Furthermore, the absence of overshoot in measured capacitance-voltage and internal charge-phosphor field curves indicates that a majority of the holes created by impact ionization are trapped at or near the phosphor/insulator interface. The multiplication factor (i.e., the total number of electrons transferred across the phosphor divided by the number of electrons injected from the phosphor/insulator cathode interface) is estimated, from device physics simulation of experimental trends, to be of the order 4-8 for evaporated ZnS:Mn ACTFEL devices operating under normal conditions.

Original languageEnglish (US)
Pages (from-to)2719-2724
Number of pages6
JournalJournal of Applied Physics
Volume77
Issue number6
DOIs
StatePublished - Dec 1 1995
Externally publishedYes

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

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