We have grown strained Si quantum wells on relaxed Si0.7Ge0.3 buffer layers using vicinal (118) silicon substrates. Compared to conventional (001) substrates the surface is tilted by 10° towards the [110] direction resulting in terraces with step edges which run parallel to [11̄0]. The surface morphology of the layers shows “cross-hatching” characteristic of relaxed SiGe films grown on Si substrates. However, the cross-hatching is not orthogonal but aligns along directions in which (111) planes intersect the (118) surface. We have measured the low temperature transport properties of the two-dimensional electron gas confined within the strained Si channel. When measured with current flowing parallel to the step edges the electron mobility is approximately four times larger than that measured in a perpendicular direction showing the strong elastic scattering associated with the step edges. In contrast the single particle relaxation time is almost identical for the two different orientations.

Abstract.We have used electrochemical anodic oxidation to form gate oxides on strained n-channel Si:SiGe quantum wells. The oxides are characterized by current-voltage and capacitance-voltage measurements. Comparison of measured and calculated electron sheet densities in the quantum well, indicates that the oxide growth does not cause degradation of the Si:SiGe material. This is confirmed by low-temperature measurements of the electron mobility and sheet density in the quantum well.

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