CdTe/CdZnTe多量子阱激子复合动力学性质的研究

EXCITON RECOMBINATION DYNAMICS IN CdTe/CdZnTe QUANTUM WELLS 

报道了分子束外延制备的高质量ＣｄＴｅ／Ｃｄ０６４Ｚｎ０３６Ｔｅ多量子阱结构的光学性质，由变温光致发光光谱讨论了随温度升高辐射线展宽和辐射复合效率降低的机理．在变密度激发的皮秒时间分辨光谱中，发现不同激发密度下发光衰减时间不同，并研究了它的机理．

Abstract Quantum wells of CdTe/CdZnTe were grown by molecular beam epitaxy. The highest order of satellite peak of the sample is 5 from XRD spectra and excition emission linewidth is about 4.8 nm at 77 K. It was shown that our samples are very good. The recombination dynamics of exciton in high quality CdZnTe/CdTe multiquantum wells were investigated by means of time resolved photoluminescence(PL) spectra with different excitation power at 77 K and photoluminescence spectra with different temperature. When weaker excitation was used, radiative recombination decay time of the exciton was reduced as the excitation intensity was decreased; the results indicate that the dominant mechanism may be the quenching of exciton emission by impurities and defects. The linewidth of the exciton emission becomes broader with increasing temperature, the linewidth at low temperature is only due to the well thickness, and the broadening linewidth at high temperature is contributed by the interactions among the exciton and LO and TO phonons and ionized donor impurities. The PL intensities are reduced with increasing temperature, which is mainly due to the thermal dissociation of excitons, i.e., the electrons or holes jump into the barriers from the wells by thermal excitations. The exciton emission from n=2 heavy hole exciton at 77 K has been observed, and the n=2 heavy hole exciton luminescence decay time is shorter than that from n=1 . The investigation indicates that there is the exciton energy relaxation from the n=2 to n=1 heavy hole exciton state by phonons.