Hot carrier type exchange in inorganic electroluminescent thin films

Abstract

The authors have observed the hot carrier type (holes or electrons) exchange in rare-earth-ion-activated strontium thiogallate (SrGa2S4) thin films by measuring the transient electroluminescent wave forms of the devices having a single insulating thin film. Measured wave forms revealed that the green electroluminescence of europium activated SrGa2S4 thin film occurs due to hot hole excitation. In contrast, the blue electroluminescence of cerium activated SrGa2S4 thin film occurs due to hot electron excitation. Hence, the hot carrier type is exchanged by the different rare-earth-ion doping.

Cover Picture: Branching Out of Single‐Molecule Fluorescence Spectroscopy: Challenges for Chemistry and Influence on Biology (Angew. Chem. Int. Ed. 18/2005)

“…The full width half‐maximum (FWHM) of the green emission band was approximately 50 nm. The green emission was similar to the one from the SrGa 2 S 4 :Eu green phosphor that has a band peaking around 540 nm and FWHM of 50 nm 2, 5, 7. The decay time of the green emission under the 266‐nm excitation was 314 µs.…”

“…This host material can be activated by using rare‐earth ions for luminescent centers, and the resulting phosphors exhibit various light emissions due to the 4f–4f and 5d–4f transitions in the inner shell of the rare‐earth ions 1, 2. In particular, Ce 3+ and Eu 2+ exhibit efficient blue and green emissions 1, and their phosphors have been studied for potential use in field‐emission displays 3, 4 and inorganic electroluminescent displays 5, 6. SrGa 2 S 4 :Eu has also been investigated as a phosphor for white light‐emitting diodes (LEDs) 7, since it can be excited by blue LEDs.…”

Luminescence Properties of Rare-Earth-Doped Thiosilicate Phosphors on Silicon Substrate

“…The excitation might be induced by hot carriers, as is proposed for inorganic EL devices. 26) Intensity (arb. unit)…”

Luminescence Properties of Rare Earth-Doped Thiosilicate Phosphors on Silicon Substrate

“…The same spectra are obtained, and the origin of EL is clearly Eu 2+ in BaSi 2 S 5 . The excitation might be done by hot electrons, as is proposed in inorganic EL devices [10].…”