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X-ray diffraction is used to probe interdiffusion in asymmetrically strained, low concentration Si/SiGe superlattices. The results are shown to be in good agreement with a model developed from literature data for Ge diffusion in SiGe alloys. Using this model, it is shown that the initial fast interdiffusion frequently observed in Si/SiGe superlattices results primarily from the concentration dependence of the activation enthalpy for SiGe interdiffusion. Time dependent strain relaxation is shown to play a discernible, but secondary role in the transition from fast to slow interdiffusion. The linear proportionality constant relating the activation enthalpy of SiGe interdiffusion to biaxial strain is found to be ~19 eV/unit strain. [ABSTRACT FROM AUTHOR]

Examines the in-diffusion of indium (In) and the surface defects introduced into silicon (Si) for various In desorption process. Reason that a lower substrate temperature and reduced in-diffusion are expected when using In; Ways in which Si surfaces were prepared; Surface morphology.

Silicon has many attractive properties for quantum computing, and the quantum-dot architecture is appealing because of its controllability and scalability. However, the multiple valleys in the silicon conduction band are potentially a serious source of decoherence for spin-based quantum-dot qubits. Only when a large energy splits these valleys do we obtain well-defined and long-lived spin states appropriate for quantum computing. Here, we show that the small valley splittings observed in previous experiments on Si–SiGe heterostructures result from atomic steps at the quantum-well interface. Lateral confinement in a quantum point contact limits the electron wavefunctions to several steps, and enhances the valley splitting substantially, up to 1.5 meV. The combination of electrostatic and magnetic confinement produces a valley splitting larger than the spin splitting, which is controllable over a wide range. These results improve the outlook for realizing spin qubits with long coherence times in silicon-based devices. [ABSTRACT FROM AUTHOR]

The recombination (electron capture) kinetics of the ionized DX center in AlxGa1-xAs have been measured as a function of temperature and silicon doping concentration. It is shown that for x[bar_over_tilde:_approx._equal_to]0.35, the silicon concentration dependence of the recombination kinetics is dominated by effects of the electron distribution in the conduction band, and is insensitive to changes in the trap characteristics. In a model kinetic calculation consistent with the data the trap is found to capture through a level 0.202 eV from the bottom of the conduction band with a width of 0.045 eV, independent of DX center concentration. [ABSTRACT FROM AUTHOR]

The article discusses the improved complementary metal oxide semiconductors (CMOS) performance via enhanced carrier mobility. According to the author, the amazing advancements achieved in Silicon CMOS have come primarily from scaling, i.e., from reducing the critical dimensions of the transistors. Since it is becoming increasingly difficult to further reduce critical dimensions such as the gate oxide thickness, alternative methods of improving transistor performance are being investigated. One approach is to increase the free carrier mobility in the active region of the device.