Electronic traps and P b centers at the Si/SiO2 interface: Band-gap energy distribution

Abstract

Energy distribution of P_b centers (⋅Si≡Si₃) and electronic traps (D_it) at the Si/SiO₂ interface in metal‐oxide‐silicon (MOS) structures was examined by electric‐field‐controlled electron paramagnetic resonance (EPR) and capacitance‐voltage (C‐V) analysis on the same samples. Chips of (111)‐oriented silicon were dry‐oxidized for maximum P_b and trap density, and metallized with a large MOS capacitor for EPR and adjacent small dots for C‐V measurements. Analysis of C‐V data shows two D_it peaks of amplitude 2×10¹³ eV⁻¹ cm⁻² at E_v+0.26 eV and E_v+0.84 eV. The EPR spin density reflects addition or subtraction of an electron from the singly occupied paramagnetic state and shows transitions of amplitude 1.5×10¹³ eV⁻¹ cm⁻² at E_v+0.31 eV and E_v+0.80 eV. This correlation of electrical and EPR responses and their identical chemical and physical behavior are strong evidence that ⋅Si≡Si₃ is a major source of interface electronic traps in the 0.15–0.95 eV region of the Si band gap in unpassivated material.