K=0 filtering in resonant-tunneling processes between materials of different effective electron mass

If electrons are transferred across an interface between an area of high and low effective mass, parallel momentum conservation leads to electron refraction effects, which are evident on InAs-AlSb resonant tunneling diodes and also, e.g., in ballistic electron emission microscopy. In ballistic electron emission microscopy on Au-GaAs Schottky diodes, the difference in effective mass is especially large and as a consequence of electron refraction, the spatial and energetic resolution for structures buried below the metal-semiconductor interface are considerably reduced. If a resonant (GaAs-AlxGa1-xAs) tunneling structure is grown directly below the sample surface, however, only electrons with zero wave vector parallel to the barriers can be transmitted resonantly. As a consequence, the energetic and spatial resolution is expected to be enhanced for buried structures. Moreover, the underlying principle can be applied to devices in order to fabricate electron injector structures with narrow energy distribution both in E⊥ and E. © 1999 The American Physical Society.