Enhanced k∥ filtering effects in ballistic electron emission experiments

Double barrier resonant tunneling diodes (DBRTD’s) buried below an Au/GaAs interface usually lead to a linear increase in the spectra obtained in ballistic electron emission microscopy/spectroscopy experiments. If grown directly below the Au/GaAs interface the spectrum changes to a clear steplike shape, which has been attributed to lateral wave-vector k∥ filtering effects. In this paper, this assertion is tested and quantified by a systematic theoretical study of these structures in terms of a coherent scattering approach as well as magnetotunneling experiments. The calculations show that the enhanced k∥ filtering is a result of the disordered Au/GaAs interface. The filtering effect is only observed for DBRTD’s grown directly beneath the Au/GaAs interface. It vanishes if the DBRTD’s are capped with 10 nm or more of GaAs. The calculated k∥ − filter width agrees well with the Shubnikov–de-Haas-like oscillations obtained from magnetotunneling experiments. © 2001 The American Physical Society.