Conduction band structure of GexSi1minus;xusing spatially resolved electron energyhyphen;loss scattering

摘要

Transmission electron energyhyphen;loss spectroscopy has been used to follow the positions of the Dgr;1andL1conductionhyphen;band minima, and theL3saddle point, as a function of Ge content in GexSi1minus;x(x=0ndash;0.95) alloys. By analyzing the shape of the Sithinsp;2prarr;conductionhyphen;band (CB) spectra we find thatL3and Dgr;1shift largely together, as the bandhyphen;structure compatibility relations predict.L1shifts rapidly downwards with respect to Dgr;1as the Ge content increases. Measurements were carried out in a scanning transmission electron microscope at a spatial resolution of better than 2 nm. Based on these results, this technique can be used to identify the composition of thin GexSi1minus;xalloys with a precision of better than 5percnt;.