Si:SiGe quantum wells grown on (118) substrates: Surface morphology and transport properties

T. J. Thornton, J. M. Fernández, S. Kaya, P. W. Green, K. Fobelets

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Abstract

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 [110]. 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.

Original languageEnglish (US)
Pages (from-to)1278-1280
Number of pages3
JournalApplied Physics Letters
Volume70
Issue number10
DOIs
StatePublished - Mar 10 1997
Externally publishedYes

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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