Temperature dependence of lateral hot-electron spreading in Au films using Cross-Sectional Ballistic Electron Emission Microscopy

Cross-sectional ballistic electron emission microscopy (XBEEM) was used to investigate the \textit{temperature dependence} of hot-electron lateral spreading in metal films. A sequence of GaAs QWs of 1 to 15 nm width (separated by 200nm Al$_{0.3}$Ga$_{0.7}$As barrier layers) were cleaved \textit{ex situ,} and then 10 nm-thick of Au was thermally deposited on the cleaved edge to form Au Schottky barrier (SB) ``nanoaperture'' contacts [1]. Previous XBEEM results showed an unexpectedly large hot-electron lateral spreading at room temperature consistent with multiple electron scattering inside the metal film [2]. If phonon scattering of hot-electrons is significant in Au films (as previously suggested [3]), then the lateral spreading should increase at lower temperature. However, we found that the lateral spreading at 80K was almost the same as at room temperature, suggesting that electron-phonon scattering is not the dominant scattering mechanism. We will also discuss the temperature dependence of the BEEM current\textit{ amplitude}, as well as Monte-Carlo simulations of the lateral spreading process. Work supported by NSF Grant No. DMR-0505165. [1] C. Tivarus \textit{et al}., PRL \textbf{94}, 206803 (2005)~ [2] C. Tivarus \textit{et al}., APL \textbf{87}, 182105 (2005) [3] L. D. Bell, PRL \textbf{77}, 319007 (1996)