Hydrostatic Pressure Studies of Optical Transitions in the PhotoluminescenceSpectra of Zn(1-x)Cd(x)Se Thick Epilayers and Zn(1-x)Cd(x)Se/ZnSe Strained Layer Multiple Quantum Wells

摘要

The effects of hydrostatic pressure (0-110 kbar) on the energy levels of bulkZn(0.86)Cd(0.14)Se in the form of a 1 micrometer thick epilayer and a six period multiple quantum well comprised of 30 A wells of Zn(0.79)Cd(0.21)Se and 400 A barriers of ZnSe (both of which are grown on GaAs substrates by molecular beam epitaxy) are studied together in the same diamond anvil pressure cell at a temperature of 14 K, enabling us to accurately determine and compare the first and second order pressure coefficients for direct gap ZnCdSe transitions in the two samples. Theoretical calculations to determine the energy levels for the quantum well sample in the presence of interlayer strain and hydrostatic pressure are carried out using the finite element method in the eight-band k(dot)p model, clearly showing the necessity of including a pressure dependent shear deformation potential. The photoluminescence (PL) intensity is irreversibly quenched in both samples by a structural phase transition occurring in ZnCdSe around 105 kbar. The effects of hydrostatic pressure on the lattice vibrational modes in the Raman spectra of bulk ZnCdSe are also studied.