Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures

• Veröffentlicht in: Semiconductor Physics Quantum Electronics & Optoelectronics
• Datum: 2007
• Hauptverfasser: Vlasenko, N.A., Oleksenko, P.F., Denisova, Z.L., Mukhlyo, M.A., Veligura, L.I.
• Format: Artikel
• Sprache: English
• Veröffentlicht: Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України 2007
• Online Zugang: https://nasplib.isofts.kiev.ua/handle/123456789/118131
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Zitieren: Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures / N.A. Vlasenko, P.F. Oleksenko, Z.L. Denisova, M.A. Mukhlyo, L.I. Veligura // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 87-90. — Бібліогр.: 13 назв. — англ.

For the first time, an anomalous strong increase of the Cr²⁺ emission intensity (I) with increasing the applied voltage (V) has been discovered in ZnS:Cr thin-film electroluminescent structures (TFELS) instead of the I(V) dependence saturation typical of TFELS of the MISIM type, where M is an electrode, I is an insulator layer and S is an EL film. The dependence of I on the transferred charge (Q) is very superlinear, whereas the luminance of the emission of hot electrons, which takes place simultaneously with the Cr²⁺ emission, increases proportionally to Q as it happens usually in TFELS. The increase of I and Q is accompanied by rising the sample temperature up to 30 – 50 °C. However, the emission spectrum that is inherent to the ⁵E → ⁵T₂ transition in the 3d shell of a Cr²⁺ ion is not changed in this case. The above effects are explained by Cr⁺ → Cr²⁺ thermofield recharging, which results in an increase of the number not only of free electrons, but also of Cr²⁺ radiation centers. The most probable mechanism of such a recharging is the Frenkel-Pool field-stimulated thermal ionization of Cr⁺ ions, whose ionization energy is 0.65…0.82 eV.