IMAGING OF LONGITUDINAL ELECTRON FOCUSING BY LIGHT-INDUCED CARRIER EXCITATION

We report on the two-dimensional observation of electron focusing unde r the influence of a longitudinal magnetic field B-l using a real spac e imaging technique. As a function of B-l the focusing patterns are mo dified and shrink together in good qualitative agreement with calculat ed focusing patterns of ballistic electrons. At low fields we observed Sondheimer oscillations periodic in B-l. At high fields light-induced magneto-oscillations due to Landau quantization occur.