Electron and hole traps in SiO2 films thermally grown on Si substrates in ultra-dry oxygen

The densities of electron and hole traps in SiO₂ films, thermally grown on Si substrates in ultra-dry oxygen, were compared with those in SiO₂ films grown in pyrogenic steam (wet-oxide films). The results show that ultra-dry-oxide films have an undetectable density of electron traps that is less that 10¹¹/cm² , and little interface-states generation during carrier injection. However, hole traps in ultra-dry-oxide films are high, (2.6±0.1)×10¹²/cm² compared with (1.3±0.2)×10¹²/cm² in wet-oxide films, and these increase by a factor of two with post-oxidation anneal in ultra-dry Ar. The results of electron spin resonance measurements of E´ centers in SiO₂ films are consistent with the results of electrical measurements. These suggest that there is a tradeoff correlation between the density of electron traps and hole traps, with respect to the amount of water- or hydrogen-related defects in SiO₂