Monte Carlo Calculations of Internal Photoemission Yields in M-I-M Thin-Film Structures

Abstract

Photomeasurements on Al–Al₂O₃–Au thin‐film sandwiches revealed a very asymmetric barrier shape, Φ₁ and Φ₂ being 1.8 and 4 eV, respectively. The image‐force lowering of the barrier can be explained by the high‐frequency dielectric constant. When photoemission measurements are performed only in the visible region, the Au electrode will not emit photoelectrons because of the large Φ₂ value. The Al electrode, however, will emit photoelectrons if the Au electrode is sufficiently positively biased. The existence of only one source for photoelectrons facilitates the interpretation of photomeasurements. Monte Carlo calculations were performed to determine the scattering of hot electrons within these films. Electron‐optical phonon scattering was assumed and a mean free path of 10 Å was found. The method to determine scattering by photoemission gives values on scattering within the image‐force region.