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Organic electroluminescence (EL) devices were fabricated using a bis(2-methyl-8-quinolinato) aluminum hydroxide complex [Al(Mq) 2 OH] as the light-emitting material. The device exhibits bright blue EL at a peak wavelength of 485 nm. A maximum luminance of about 14,000 cd/m 2 can be achieved at a driving current density of 480 mA/cm 2 . The efficiency of the device is about 4.6 cd/A. Possible mechanisms of EL blue shift of Al(Mq) 2 OH with respect to Alq 3 are discussed.

We investigated the relationship between Sn precipitation and strain relaxation in Ge 1Àx Sn x buffer layers grown by the compositionally step-graded (CSG) method on a virtual Ge substrate. We found that the strain in the upper Ge 1Àx Sn x layers is reduced by Sn precipitation rather than the lateral propagation of misfit dislocations at the interfaces of upper Ge 1Àx Sn x layers in the CSG method. The critical misfit strain was increased to 5:8 Â 10 À3 compared with that in our previous work by lowering the temperature of the postdeposition annealing, and a Sn content of 6.3% in the Ge 1Àx Sn x buffer layer was achieved with a large degree of strain relaxation using only two stacked layers of the CSG structure. An in-plane tensile strain of 0.62% in a 30-nm-thick Ge layer fabricated on these Ge 1Àx Sn x buffer layers was achieved. #

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