Luminescence study of ZnTe:Cr epilayers grown by molecular-beam epitaxy
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- Luo, M., Vanmil, B.L., Tompkins, R.P. et al. Journal of Elec Materi (2003) 32: 737. doi:10.1007/s11664-003-0062-x
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Incorporation of Cr into ZnTe epilayers grown by molecular-beam epitaxy (MBE) is reported. Photoluminescence (PL) using both continuous wave (CW) and pulsed-excitation sources is used to characterize the radiative efficiency of doped layers in the infrared region. The Cr2+ ions produce a broad emission band peaking in the 2–3 µm range, which is of potential use in tunable-laser devices. The optimum Cr concentration for achieving bright, room-temperature infrared emission was found to be in the range from low- to mid-1018 cm−3. Temperature-dependent luminescence studies were performed to determine thermal-quenching activation energies. Using a pulsed-laser operating at 1.9 µm, an investigation of emission lifetimes was made. The emission-decay curves for the Cr2+ recombination in ZnTe:Cr films could be described by a single exponential and were nearly independent of temperature from 80 K to 300 K. A room-temperature lifetime of ∼2.5 µsec in a ZnTe:Cr layer with [Cr] ∼1.4 × 1018 cm−3 compares favorably with values reported for bulk ZnTe:Cr.