Photoluminescence spectra of CdTe multi-quantum wells sandwiched by ultrathin MnTe layers and their temperature dependence

Abstract

To study the energy transfer (ET) between the Mn2+ intra-center luminescence (IL) state and the band state in CdTe quantum wells (QWs), we studied the temperature dependences of the photoluminescence (PL) spectra of the CdTe multi-QWs sandwiched by ultrathin MnTe layers and found an anomalous thermal variation of their PL intensities. With elevating temperature, the PL intensities of the thinner QWs having 4 and 8 monolayers (MLs) remain at rather high temperatures than 100K despite the PL of the thicker QWs disappears rapidly. In the thinner QWs, the PL bands appear in an overlap region with the Mn2+ IL-band and energy transfer is expected between the IL-state and the band states in the thinner QWs. The anomalous thermal variations of the PL intensities can be explained by considering the ET and the role of Mn2+ IL-state as reservoir states against the thermal quenching processes.