Microstructural and morphological properties of homoepitaxial (001)ZnTe layers investigated by x-ray diffuse scattering

The microstructural and morphological properties of homoepitaxial (001)ZnTe layers are investigated by x-ray diffuse scattering. High resolution reciprocal space maps recorded close to the ZnTe (004) Bragg peak show different diffuse scattering features. One kind of cross-shaped diffuse scattering streaks along directions can be attributed to stacking faults within the epilayers. Another kind of cross-shaped streaks inclined at an angle of about 80deg with respect to the in-plane direction arises from the morphology of the epilayers. (abridged version

Controlled Nucleation and Growth of CdS Nanoparticles in a Polymer Matrix

In-situ synchrotron X-ray diffraction (XRD) was used to monitor the thermal decomposition (thermolysis) of Cd thiolates precursors embedded in a polymer matrix and the nucleation of CdS nanoparticles. A thiolate precursor/polymer solid foil was heated to 300 degrees C in the X-ray diffraction setup of beamline W1.1 at Hasylab, and the diffraction curves were each recorded at 10 degrees C. At temperatures above 240 degrees C, the precursor decomposition is complete and CdS nanoparticles grow within the polymer matrix forming a nanocomposite with interesting optical properties. The nanoparticle structural properties (size and crystal structure) depend on the annealing temperature. Transmission electron microscopy (TEM) and photoluminescence (PL) analyses were used to characterize the nanoparticles. A possible mechanism driving the structural transformation of the precursor is inferred from the diffraction features arising at the different temperatures

Low pressure MOVPE growth and structural properties of ZnMgSe epilayers on (100)GaAs

The low-pressure MOVPE growth of ZnMgSe on (100)GaAs is reported. ZnMgSe alloys were deposited after a thin pseudomorphic ZnSe buffer layer by using dimethylzinc:triethylammine (Me2Zn:Et3N), ditertiarylbutilselenide (tBu2Se) and bis(methylcyclopentadienyl)magnesium [(MeCp)2Mg]. Zn1-xMgxSe (0.10 <x < 0.46) epilayers were grown at 330°C, 304 mbar and a high VI/II ratio in the vapour. Under these conditions the growth is limited by the mass transport of the II-group alkyls and good control of the composition was achieved. Rutherford backscattering spectrometry measurements allowed to determine the epilayer stoichiometry and deposited dose. The ZnMgSe solid-vapour distribution curve deviates from linearity due to the different Mg and Zn alkyl vapour diffusion coefficients, whose ratio turns out to be D-(MeCp)2Mg/D-Me2Zn = 0.410. The epilayer crystalline properties were studied by double-crystal X-ray diffraction (DC-XRD) and high-resolution reciprocal space mapping (RSM) measurements. Rocking curve FWHM values of 540-900 nm thick Zn1-xMgxSe were in the 5-12 mrad range, indicating the occurrence of extended defects in the epilayers. RSM measurements in the vicinity of the (400)-peak of a Zn0.844Mg0.156 Se/ZnSe(100)GaAs sample showed a slight asymmetry of the ternary alloy peak along the growth direction, ascribed to an inhomogeneous relaxation of the epilayer