The use of synchrotron radiation techniques in the characterization of strained semiconductor heterostructures and thin films

High crystalline quality zinc-blende structure Zn(1−x)MgxSe epitaxial layers were grown on InP (001) substrates by molecular beam epitaxy. Their band gap energies were determined as a function of Mg concentration and a linear dependence was observed. The band gap of the Zn(1−x)MgxSe closely lattice matched to InP was found to be 3.59 eV at 77 K and the extrapolated value for zinc-blende MgSe was determined to be 3.74 eV. Quantum wells of Zn(1−x)CdxSe with Zn(1−x)MgxSe as the barrier layer were grown which exhibit near ultraviolet emission.

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Molecular beam epitaxial growth and characterization of zinc-blende ZnMgSe on InP (001)

We report the dependence of the growth and the optical properties of self-assembled CdTe/Zn1−xMgxTe quantum dots on the barrier Mg content x (0⩽x⩽0.3). Due to the decrease of the lattice mismatch between CdTe and Zn1−xMgxTe with increasing x, we use a technique for inducing dot formation, based on efficient reduction of the surface energy by deposition of amorphous Te, which is then desorbed. Mg incorporation in the barriers leads to a better heavy-hole confinement along the growth axis, which is manifested in photoluminescence (PL) studies by both an extension of the radiative regime temperature range (up to 150 K for 30% Mg) and a strong increase of the activation energy for the nonradiative recombination. However, the in-plane confinement is less enhanced, which allows observation of interdot carrier transfer with increasing temperature, as evidenced directly by the analysis of PL intensities for different single dots. Our temperature-dependent data (time-resolved and microphotoluminescence) suggest th...

CdTe/Zn1-xMgxTe self-assembled quantum dots: Towards room temperature emission

Semiconductor nanocrystal compositions comprising magnesium containing shells and methods of preparing them are described. The compositions provide strong emission in the blue and green wavelengths as well as chemical and photostability that have not been achieved with conventional shell materials.

Th. Reisinger

Papers

Gap Energies, Exciton Binding Energies and Band Offsets in Ternary ZnMgSe Compounds and ZnSe/ZnMgSe Heterostructures