| Autor: |
Ming Luo, VanMil, B. L., Tompkins, R. P., Myers, T. H., Giles, N. C. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 1/1/2005, Vol. 97 Issue 1, p013518, 8p, 11 Graphs |
| Abstrakt: |
Photoluminescence (PL) from undoped and chromium-doped ZnTe epilayers was studied in the spectral range from 0.3 to 2.4 eV over the temperature range from 5 K to room temperature. Films approximately 2 μm thick were grown by molecular-beam epitaxy on GaAs substrates. For undoped ZnTe, spectra are dominated by a sharp acceptor-bound-exciton line related to arsenic, with only weak emission observed due to substitutional oxygen (OTe). An analysis of strain-induced shifts in excitonic energies was performed to clarify transition assignments for two PL bands near 2.375 and 2.379 eV. For ZnTe:Cr epilayers, the infrared Cr2+ emission near 2.5 μm (0.5–0.6 eV) was found to be a function of both doping concentration and Zn/Te beam-equivalent-pressure ratio. Direct excitation of the Cr2+ ions with 1.89-μm light produced emission up to room temperature. Indirect excitation with 514.5-nm light produced emission that could be detected up to 180 K. Luminescence decay curves measured from a ZnTe:Cr film ([Cr]∼1×1018 cm-3) using pulsed excitation at 355 and at 532 nm indicated two lifetimes: τ1=3 (±1) μs and τ2>=10 μs. The shorter lifetime agrees with values reported previously for Cr-doped ZnTe bulk crystals and thin films under 1.9-μm pulsed excitation. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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