| Research Abstract |
In this investigation, we grew the ZnSe-ZnTe strained superlattices with a dual subband (DSB) structure of [(7, 2)_6(2, 5)_1]_100. The structure and the mechanism of light up-conversion effect are analyzed by the HRXD, Raman scattering and measurements of excitation intensity dependences of PL spectra. The HRXD spectra indicate the satellite peaks of 0, ±1 and - 2 order of the part of (7, 2)_6. The diffraction peaks coincide with the result of calculated simulation. The Raman spectrum shows the ZnSe-like LO and the ZnTe-like LO phonon peaks, which means the sample consists of individual ZnTe layer. The PL spectra showed two peaks at 1.8 and 2.2 eV. The peak at 2.2 eV is from the part of (7, 2)_6 in the superlattice. In the previous investigation, the sample of the structure of [(2, 2)_<12>(2, 5)_3]_<30> indicated the PL peaks at 1.9 and 2.2 eV. It is cleared that we are able to control the photon energy of PL peaks by the structure of the DSB superlattices. The PL peak at 2.2 eV appeared also by excitation with the He-Ne laser, the energy of which is 1.96 eV, I.e., the laser light of 1.96 eV is converted to the light with the energy 2.2 eV (up-conversion). The dependence of the intensity of the 2.2 eV peak on the excitation intensity pointed out a non-linear relation. It is considered the mchanism of the up-conversion involves a step process of transition.
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