The Neutral Level of Si-SO2 Interface States

Abstract

From measurements of the temperature dependence of barrier height in Cr — SiO2 — n—Si structures, we have determined the oxide charge, the charge and density of Si — SiO2 interface states, and the position of their neutral level. A negative oxide charge is observed which is attributed to acceptor-type states in the oxide populated by tunneling electrons. The extracted interface state density agrees with other techniques and the high temperature data support trap-assisted tunneling as the dominant recombination mechanism of holes in weak inversion. The neutral level is found 0.1 ± 0.07 eV above midgap of silicon. This is consistent with a distribution of donor states above and acceptor states below the midgap level.