Influence of the preparation and excitation conditions of ZnS:Er,F TFELS on the radiative characteristics in the visible and near‐infrared spectral regions

Abstract— The voltage (V) dependences of the luminance and transferred charge of ZnS:Er,F TFELS prepared by varying the annealing temperature (Tann) are given at different frequencies (f). The change in the relative intensity of the green band (523 nm) and the near‐infrared bands (983 and 1530 nm) in the emission spectrum when V, f, and Tann are varied is also considered. The influence of the annealing temperature on the energy spectrum of defects in ZnS:Er,F film was studied by photodepolarization spectroscopy. The revealed effect of the above excitation and preparation conditions on the radiative characteristics is discussed.     

Near‐infrared‐emitting ZnS: Er and ZnS(Se): Cr TFEL devices

Abstract— Electroluminescent near‐infrared (NIR) emitters are of interest in creating special displays for applications such as communications, chemical sensoring, friend‐and‐foe identification, aligning and checking systems that detect NIR radiation, medicine, etc. By performing this research, known NIR emitters (thermal sources, semiconductor diodes and lasers, and solid‐state lasers) were supplemented by NIR‐emitting TFEL devices based on ZnS: Er(F) and ZnS(Se): Cr electron‐beam‐evaporated films. Some characteristics of these devices as NIR emitters are given. There are two narrow intensive bands at ^～980 and ～1530 nm in the emission spectrum of ZnS: Er(F) TFEL devices. The broadband emission is the range of from 1.8 μm up to 2.7 μm takes place in the ZnS(Se): Cr devices. The wavelength of the peak emission can be varied owing to interference. The mechanism of electroluminescence in the ZnS: Er(F) and ZnS(Se): Cr devices is the direct impact excitation of Er³⁺ and Cr²⁺ ions, respectively.     

Subthreshold voltage‐induced transferred charge measurements of evaporated ZnS:Mn alternating‐current thin‐film electroluminescent devices

Subthreshold voltage‐induced transferred charge (VIQ) analysis is proposed as a novel method for assessing the nature of aging in alternating‐current thin‐film electroluminescent (ACTFEL) devices. VIQ analysis involves the application of 20,000 bipolar voltage pulses of variable amplitude and measurement of the subthreshold charge transferred in the phosphor for voltage amplitudes from 0 V to threshold. VIQ experiments provide information related to the physical location, density, energy depth, and capture cross‐section of phosphor traps responsible for ACTFEL device aging. VIQ aging experiments were performed on ZnS:Mn ACTFEL devices whose phosphor layers were deposited by thermal evaporation, atomic layer epitaxy using chlorine as a constituent of the precursor gas [ALE (Cl)], and atomic layer epitaxy with diethyl zinc as a precursor gas [ALE (DEZ)]. The depth of the traps responsible for VIQ in evaporated, ALE (Cl), and ALE (DEZ) ZnS:Mn are estimated to be ～1.0–1.2, ～0.3, and ～0.7–0.9 eV, respectively. It is speculated that the traps responsible for VIQ are due to sulfur vacancies, chlorine, and oxygen, for evaporated, ALE (Cl), and ALE (DEZ), respectively.     

Fabrication and performance characteristics of black‐dielectric electroluminescent 160 × 80‐pixel displays

Abstract— We report on recent technological progress in black‐dielectric electroluminescent (BDEL) displays. Fabrication of the first monochrome BDEL 160 × 80‐pixel 4‐in. displays driven with commercial low‐power (<5 W) drive circuitry is presented. Preliminary results on blue‐dielectric EL full‐color displays are also reported. Improvements in both BDEL display performance and display manufacturability underscore the recent development path.     

The new route for realization of 1‐μm‐pixel‐pitch high‐resolution displays

A new pixel structure for the realization of a 1‐μm‐pixel‐pitch display was developed. This structure, named vertically stacked thin‐film transistor (VST), was based on the conventional back‐channel etched thin‐film transistor (TFT), but all the layers except the horizontal gate line were vertically stacked on the embedded data line, enabling the implementation of high‐resolution display panels. The VST device with a channel length of 1 μm showed a high field effect mobility of more than 50 cm²/Vs and low subthreshold slope of 78 mV per decade. It also shows a high uniform electrical characteristic over the entire 6‐in. wafer. The development of a new pixel architecture is expected to enable the implementation of 1‐μm‐pixel‐pitch high‐resolution displays such as spatial light modulators for digital holograms.