A simple model for the hysteretic behavior of ZnS:Mn thin film electroluminescent devices

Howard, W. E.; Sahni, O.; Alt, P. M.

doi:10.1063/1.329971

Cited by 111 publications

(21 citation statements)

References 15 publications

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“…The 7.3ϫ10 16 cm Ϫ3 static space charge estimate of Ohmi et al 13 is within the range of our estimate. Moreover, this static space charge estimate is comparable to the 5.0ϫ10 16 cm Ϫ3 experimental value of the trapped hole concentration deduced by Howard et al 21 in their analysis of hysteretic behavior in ZnS:Mn ACTFEL devices. Although Ohmi et al 13 and our ACTFEL devices do not exhibit brightness-voltage hysteresis, it seems likely that the hole trapping mechanism proposed by Howard et al could be the origin of static space charge.…”

Section: A Estimation Of the Static Space Charge Densitysupporting

confidence: 78%

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Static space charge in evaporated ZnS:Mn alternating-current thin-film electroluminescent devices

Hitt

Keir

Wager

et al. 1998

Journal of Applied Physics

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The operation of alternating-current thin-film electroluminescent (ACTFEL) devices may be strongly affected by the presence of dynamic or static positive space charge within the phosphor layer during device operation. Dynamic space charge is a positive charge in the phosphor layer which is periodically created and annihilated during each period of the applied voltage waveform. In contrast, static space charge is a positive space charge in the phosphor layer whose charge state does not change appreciably during steady-state operation of the ACTFEL device. The static space charge density of evaporated ZnS:Mn ACTFEL devices is estimated to be ∼7×1016 cm−3 from measured trends in the phosphor clamping field as a function of phosphor thickness. This static space charge density estimate implies a cathode clamping field of ∼ 2.2 MV/cm and a clamping interface trap depth of ∼1.5 eV. Furthermore, from transferred charge trends as a function of the phosphor thickness it is concluded that the static space charge in evaporated ZnS:Mn ACTFEL devices arises from metastable hole trapping in the phosphor.

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Section: A Estimation Of the Static Space Charge Densitysupporting

confidence: 78%

“…It is interesting to speculate on the physical nature of these hole traps. Howard et al 21 proposed that the deep hole traps responsible for B -V hysteresis arise from the formation of Mn complexes. It is possible that static space charge is associated with such Mn complexes.…”

Section: B the Origin Of Static Space Chargementioning

confidence: 99%

Static space charge in evaporated ZnS:Mn alternating-current thin-film electroluminescent devices

Hitt

Keir

Wager

et al. 1998

Journal of Applied Physics

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“…The presence of Mn could be a source of the ''hysteresis'' phenomenon, since Mn is well known as the cause of a similar hysteresis phenomenon in ZnS. 22 Another possibility is the existence of Eu-related deep traps, which can also explain the high resistivity of our samples. The occurrence of divalent Eu ion ͑Eu 2ϩ ), possibly through electron transfer or impact ionization, was also considered but no Eu 2ϩ -related broad emission was detected.…”

Section: ͓S0003-6951͑00͒04312-6͔mentioning

confidence: 95%

Voltage-controlled yellow or orange emission from GaN codoped with Er and Eu

Lee

Heikenfeld

Birkhahn

et al. 2000

Applied Physics Letters

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Orange and yellow-colored light emission has been achieved at room temperature in the same elecroluminescent device (ELD) made on GaN thin films codoped with Er and Eu. The GaN film was grown by molecular-beam epitaxy on Si (111) substrates using solid sources for Ga, Er and Eu and a plasma source for N2. Simple Schottky devices were fabricated on the GaN films using indium–tin oxide (ITO) transparent electrodes. ELD spectra show that the yellow and orange colors result from the combination of green emission from Er (537, 558 nm) and red emission from Eu (621 nm). A color change was observed with applied bias, producing yellow at higher bias (−100 V) and orange at lower bias (−70 V). We have fabricated both relatively small (∼250 μm) and large (1.45 mm) ELDs. Parameters for the chromaticity diagram were calculated to be x=0.382, y=0.605 for the yellow emission and x=0.467, y=0.523 for the orange emission. This work shows the possibility of achieving any intermediate color in the spectrum from green to red by adjusting the concentration of Er and Eu in GaN.

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“…their inherent memory, results from the existence of a hysteresis in the voltage (V) dependences of the luminance (L) and the transferred charge (Q) [6,7]. The hysteresis in these characteristics is due to a positive feedback between three main physical processes proceeding in TFELS: the tunnel injection of initial free electrons, the impact multiplication of these free electrons, and the formation of a positive space charge (PSC) which results in an enhancement of the field in the ZnS : Mn film [8][9][10][11][12]. Main centers which are responsible for the impact formation of PSC are isovalent traps ½Mn 2þ…”

Section: Introductionmentioning

confidence: 99%

Temperature Effects on Self-Organized Patterns and Characteristics of Bistable ZnS:Mn Thin-Film Structures

Vlasenko

Purwins

Попов

et al. 2002

phys. stat. sol. (a)

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A temperature (T) rise from 20 up to 80 °C results in some decrease of the threshold voltage and slope of the voltage (V) dependences of the luminance and the transferred charge of the electron‐beam evaporated ZnS:Mn ac thin film electroluminescent structures (ac TFELS) showing different patterns or no patterns in the emission. Such a heating leads to an improvement of the dynamics of all the patterns, to a narrowing and acceleration of the autowave (AW) front. However, the dynamic patterns are not formed by such a heat treatment if they are absent at any frequency of V and T = 20 °C. Although AWs more often take place at 70–80 °C, they have also been observed at T ≤ 40 °C in some samples. It has been concluded that heating is not a sufficient condition for the formation of patterns. It enhances the generation of initial free electrons at a given V, promotes a lateral spreading of the non‐equilibrium charge carriers, but decreases the rate of all processes responsible for the bistability of the TFELS and the self‐organization in them.

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A simple model for the hysteretic behavior of ZnS:Mn thin film electroluminescent devices

Cited by 111 publications

References 15 publications

Static space charge in evaporated ZnS:Mn alternating-current thin-film electroluminescent devices

Static space charge in evaporated ZnS:Mn alternating-current thin-film electroluminescent devices

Voltage-controlled yellow or orange emission from GaN codoped with Er and Eu

Temperature Effects on Self-Organized Patterns and Characteristics of Bistable ZnS:Mn Thin-Film Structures

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