Influence of twinned structure on the morphology of CdTe(111) layers grown by MOCVD on GaAs(100) substrates
Abstract The morphology and structure of CdTe(1 1 1) layers grown on GaAs(1 0 0) by MOCVD have been studied by atomic force microscopy (AFM) and X-ray texture analysis. Growth conditions have been chosen so that mirror-like CdTe layers are obtained. Layers whose growth times vary between 10 s and 2 h have been investigated. The X-ray texture analysis shows that the CdTe layers grown on GaAs substrates that were thermally treated at 580°C for 30 min in a H 2 atmosphere exhibit a (1 1 1) preferential orientation and are twinned. This twinned structure of the (1 1 1)CdTe layer which is observed as 60° rotated triangular crystallites in the AFM images strongly influences the surface morphology.…
Room-temperature vibrational properties of potassium gadolinium double tungstate under compression up to 32GPa
Abstract KGd(WO 4 ) 2 has been studied by high-pressure Raman spectroscopy at room temperature up to 32.2 GPa. Evidences of two pressure-driven phase transitions have been detected. The low-pressure monoclinic phase undergoes a phase transition at 7.2(±0.9) GPa. The second transition is found at 14.2(±1.6) GPa. Both transitions are reversible. No evidence of pressure-induced amorphization is found up to 32 GPa. The pressure dependence of the Raman active modes of the low- and high-pressure phases is reported. A Raman mode is detected to exhibit a weak softening in the low-pressure phase. Three Raman modes are also observed to have a similar behavior in the second high-pressure phase. The re…