Study of Silicon-Silicon Dioxide Structure by Electron Spin Resonance I

Three kinds of paramagnetic centers named P_A, P_B and P_C have been found in a silicon-silicon dioxide structure at liquid nitrogen temperature. P_A (g=∼2.000, ΔH=∼4 Oe), and P_B having anisotropic g-value (g=∼2.000∼2.010, ΔH=∼6 Oe) are in the exide, while P_C which also has anisotropic g-value (g=∼2.06∼2.07, ΔH=∼9 Oe) is in the silicon near the Si-SiO₂ interface. Distribution of P_B is successfully determined that it has the maximum concentration within about 400Å from the interface. P_A and P_B appear when the silicon is oxidized in dry oxidizing ambient or the Si-SiO₂ is cooled from elevated temperatures to room temperature with a cooling speed of about 500°C/sec. P_C appears when the Si-SiO₂ is heated at elevated temperatures followed by rapid cooling to room temperature or is exposed to the ambient containing an appreciable amount of hydrogen at elevated temperatures such as 1000°C, for 10 min. P_B is ascribed to a trivalent silicon \overset\shortmid\underset\shortmid-Si· which has a nonbonding orbital electron in the Si-O network. The mechanisms for the various behaviors of the centers are also discussed in detail.