Volume 100, Issue 7, 01 October 2006
Index of content:
100(2006); http://dx.doi.org/10.1063/1.2354318View Description Hide Description
We report on our study of the effects of interdot coupling on the properties of quantum dot infrared photodetectors. The main effect we address here is the splitting of the optical absorption of coupled quantum dots due to electron hopping between the dots. The splitting depends on the size of the dots and the interdot distance and it can be observed only for small dots, less than . The system is studied numerically within the effective mass approximation.
100(2006); http://dx.doi.org/10.1063/1.2354586View Description Hide Description
Thin films with ultrafine Si nanocrystals and ultraviolet (UV) light emission were prepared by using reactive sputtering of and Al targets. The reaction of Al and leads to the formation of ultrafine Si nanocrystals with compact shell. shell retards the growth of Si nanocrystals and provides ideal passivation on Si nanocrystals. Intrinsic UVphotoluminescence is ascribed to the quantum-confinement effect of Si nanocrystals.
100(2006); http://dx.doi.org/10.1063/1.2356092View Description Hide Description
Ordinary fired ceramics show a gradual reduction in their room temperature after annealing at temperatures from room temperature to . Textured ceramics show a greater resistance to thermal depoling. At about there is a rapid drop of for the textured materials, which may be a consequence of a phase transition. Between 500 and the is stable. The depolarization is assisted by internal mechanical stresses. These stresses are smaller in textured materials, which explains the increasing resistance to thermal depoling with increasing texture.
100(2006); http://dx.doi.org/10.1063/1.2356093View Description Hide Description
which has a hexagonal structure similar to that of is found to show a canted antiferromagnetic behavior below and a ferroelectric(FE)transition at accompanied by hystersis. We have determined the structure, polarization, and energetics of the FE and paraelectric (PE) phases of using first-principles density functional theory calculations based on pseudopotentials and a plane-wave basis, and find the polarization of the PE phase to be a half-integer quantum. The difference in polarization of the FE and PE phases calculated along a simple path is different from the absolute value of polarization of the FE phase. A weak piezoelectric response is exhibited by to uniaxial strain.