Electron refraction in ballistic electron-emission microscopy studied by 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 distribution in ballistic electron-emission microscopy (BEEM) at room temperature and T = 100 K. Due to the large difference in electron masses in Au and GaAs we find that parallel momentum conservation leads to considerable electron refraction at the Au-GaAs interface. As a consequence, the energetic distribution of the ballistic electron current is inverted 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].