Semiconductor Device Group

 

The degeneracy of both the conduction band and valance band is broken by the application of either tensile or compressive strain. The appropriate splitting for the silicon-like band structure below Ge contents of 85% is shown on the right.

 

 

There are two components to the strain which changes the band structure of materials. Hydrostatic strain (due to the fractional volume change) shifts the energy of a band. Uniaxial strain splits the degeneracy of bands e.g. the valleys in the conduction band of silicon and the degenerate LH and HH valence band edge.

 

The hydrostatic shift and uniaxial splititing of the conduction and valence bands for (100) substrates are shown above for both compressive and tensile strain. Deformation potentials determine the exact amount of splitting which can be measured experimentally.