Contactless Characterization of Thermally Oxidized, Air-Exposed and Hydrogen-Terminated Silicon Surfaces by Capacitance-Voltage and Photoluminescence Methods

Abstract

Contactless and nondestructive characterization of the electrical properties of the free surfaces of single-crystalline silicon wafers is accomplished for the first time by combined use of the contactless metal-insulator-semiconductor (MIS) capacitance-voltage (C-V) technique and the photoluminescence surface state spectroscopy (PLS3) technique. The thermally oxidized, air-exposed and hydrogen-terminated silicon (111) surfaces were investigated. Thick thermally oxidized surfaces showed well-behaved characteristics with a minimum of a broad U-shaped interface state density (N ss) distributions in a range of 1010 cm-2eV-1. On the other hand, the air-exposed Si surface exhibited a GaAs MIS-like behavior with strong Fermi level pinning near the charge neutrality level E HO caused by a narrow U-shaped state distribution. Surprisingly, hydrogen-terminated surfaces showed even stronger Fermi level pinning at E0 = E c - 0.43 eV due to high density of amphoteric discrete state which may be due to silicon dangling bonds.