Hole trap analysis in SiO₂/Si structures by electron tunneling

Hole trap parameters in Si/SiO 2 structures are investigated by their charge relaxation after a foregoing hole trap population. A concept based on tunneling between extended Si states and localized SiO 2 states is developed to explain the logarithmic time dependence, gate voltage dependence, and temperature dependence of hole trap depopulation. A positively charged hole trap level with a trap energy of E = (6.3 ± 0.2) eV above the SiO 2 valence band edge is found. The corresponding value of the wave vector is | K ( E )| = 6.1 nm −1 according to the two‐band approximation for the K ( E ) relation in the SiO 2 gap. The hole trap concentration is N = 2 to 5 × 10 19 cm −3 inside a small (5 nm) near‐interface region. These results are in agreement with EPR experiments and confirm that the E'‐centre (oxygen vacancy) constitutes a dominating paramagnetic defect and a hole trap.