BALLISTIC-ELECTRON-EMISSION MICROSCOPY OF STRAIN NONUNIFORMITIES IN SI1-XGEX SI STRUCTURES/

Ballistic-electron-emission microscopy (BEEM) is used to probe local c onduction-band structure in strained Si1-xGex layers of pseudomorphic Si1-xGex/Si heterostructures. The strain variation produced by a rough ened Si1-xGex surface is seen as a variation of splining between thres holds in BEEM spectroscopy. This splitting is directly related to the strain-induced conduction-band splitting in the Si1-xGex layer, enabli ng BEEM to directly measure local strain variations. Elasticity calcul ations for a roughened Si1-xGex surface predict variations in strain t hat are consistent with BEEM observations. For the case of a smooth Si 1-xGex surface, a uniform conduction-band splining is observed that is in good agreement with calculations.