Measurements of local strain variation in Si1-xGex/Si heterostructures

Abstract

The energy splitting of the conduction-band minimum of Si1-xGex due to strain has been directly measured by the application of ballistic-electron-emission microscope (BEEM) spectroscopy to Ag/Si1-xGex structures. Experimental values for this conduction-band splitting agree well with calculations. For Au/Si1-xGex, however, heterogeneity in the strain of the Si1-xGex layer is introduced by deposition of the Au. This variation is attributed to species interdiffusion, which produces a rough Si1-xGex surface. Preliminary modeling indicates that the observed roughness is consistent with the strain variation measured by BEEM.