Experiments on Mercury-Silicon Surface Barriers

Abstract

Barrier heights of Si‐Hg surface barriers were examined experimentally as a function of the resistivity of the silicon. The saturation reverse current and the resistance at zero bias for the diodes were measured. The simplest Schottky metal‐semiconductor theory reasonably explains the resistivity‐dependent behavior of ``n''‐type Si. However, for ``p''‐type Si a surface inversion layer is predicted if the published work functions are superposed on the simplest model. Here the resistivity dependence for the thicker barriers is less strong and the measurements more variable. The results are summarized in terms of the flat band condition (u_B=u_S) in units of kT/q from midband: Calculated 3±3.5. The experiments are consistent with 3±5, using no surface states to improve the fit. A Shockley surface‐charge distribution ±n_ss≲10¹²/cm² is sufficient to suit the experimental data to u_B=3. Sample treatments were ion bombardment with Hg ions, followed by submersion in Hg. Field enhanced desorption in liquid Hg was also used. Cleaved samples produced what seemed to be patchy surfaces with small regions degenerate ``p'' type.