BALLISTIC-ELECTRON-EMISSION MICROSCOPY OF STRAINED SI1-XGEX LAYERS

Ballistic-electron-emission microscopy (BEEM) has been used to investigate the effects of strain on Si1-xGex alloys. Lifting of the degeneracy of the conduction-band minimum of Si1-xGex due to lattice deformation has been directly measured by application of BEEM spectroscopy to Ag/Si structures. Experimental values for this conduction-band splitting agree well with calculations. In addition, an unexpected heterogeneity in the strain of the Si1-xGex layer is introduced by deposition of Au. This effect, not observed with Ag, is attributed to species interdiffusion and has important implications for metal-semiconductor devices based on pseudomorphic Si1-xGex/Si material systems.