ELECTRON REFRACTION IN BALLISTIC-ELECTRON-EMISSION MICROSCOPY STUDIEDBY A SUPERLATTICE ENERGY FILTER

Buried Al0.4Ga0.6As/GaAs superlattices on Au-GaAs Schottky diodes have been used as an energy filter to study the energetic current distribu tion in ballistic electron-emission microscopy (BEEM) at room temperat ure and T = 100 K. Due to the large difference in electron masses in A u and GaAs we find that parallel momentum conservation leads to consid erable electron refraction at the Au-GaAs interface. As a consequence, the energetic distribution of the ballistic electron current is inver ted beyond the Au-GaAs interface and an almost linear behavior of the BEEM spectrum is observed in the energetic regime of the superlattice miniband. [S0163-1829(98)51136-8].