Valley splitting in Si quantum dots embedded in SiGe

S. Srinivasan, G. Klimeck, L. P. Rokhinson
2008 Applied Physics Letters  
We examine energy spectra of Si quantum dots embedded into Si_0.75Ge_0.25 buffers using atomistic numerical calculations for dimensions relevant to qubit implementations. The valley degeneracy of the lowest orbital state is lifted and valley splitting fluctuates with monolayer frequency as a function of the dot thickness. For dot thicknesses <6 nm valley splitting is found to be >150 ueV. Using the unique advantage of atomistic calculations we analyze the effect of buffer disorder on valley
more » ... tting. Disorder in the buffer leads to the suppression of valley splitting by a factor of 2.5, the splitting fluctuates with 20 ueV for different disorder realizations. Through these simulations we can guide future experiments into regions of low device-to-device fluctuations.
doi:10.1063/1.2981577 fatcat:p3pqpls23fe4ngj3vqq3dmwnwm