MEASUREMENT OF THE ZERO-BIAS ELECTRON TRANSMITTANCE AS A FUNCTION OF ENERGY FOR HALF-ELECTRON-WAVELENGTH AND QUARTER-ELECTRON-WAVELENGTH SEMICONDUCTOR QUANTUM-INTERFERENCE FILTERS

Ballistic electron emission spectroscopy has been used to measure the electron transmittance function of both half-and quarter-electron-wave length (using optics terminology) quantum-interference filters under z ero applied voltage bias. At the design energy, these devices exhibit constructive and destructive interference, respectively. Second-deriva tive spectra from current versus voltage measurements clearly show bot h tunneling and above-barrier quasibound energy states. The spectra ac curately reproduce the transmittance functions of the designed structu res, attaining nearly the temperature-limited resolution at 77 K and 3 00 K. The presence of the above-barrier resonances has been confirmed conclusively by measurements on these complementary half-and quarter-w avelength device structures. (C) 1998 American Institute of Physics.