PHOTOLUMINESCENCE OF ZNSE ZNMNSE SUPERLATTICES UNDER HYDROSTATIC-PRESSURE

Photoluminescence near 4450 angstrom (violet) and 5900 angstrom (yello w) from ZnSe/Zn1-xMnxSe strained-layer superlattices (SLS) is studied as a function of applied hydrostatic pressure up to approximately 90 k bar for x = 0.23, 0.33, and 0.51 at 9 K. For each of the three SLSs, t he peak energy of the near-band-gap violet photoluminescence (PL) from exciton recombination increases sublinearly with pressure, and closel y follows that of ZnSe. The observed dependence is consistent with typ e-I band alignment, at least at pressures where the violet PL intensit y remains strong. For the x=0.23 SLS, the energy of the biexciton PL i ncreases faster than that of the exciton, which suggests decreased con finement. The yellow PL is due to the 4T1 --> 6A1 intraionic transitio n in Mn 2+ and the nearly linear decrease of the peak energy of this s ignal with pressure is explained by crystal-field theory. In most case s examined, the intensities of the violet and/or yellow PL decrease ab ruptly above a certain pressure that increases with x from approximate ly 65 to approximately 90 kbar. For the different cases, this suggests either the occurrence of a phase transition in the ZnxMn1-xSe layers or a band crossing.