Inherent point defects at the thermal higher-Miller index (211)Si/SiO₂ interface

Electron spin resonance (ESR) studies were carried out on the higher-Miller index (211)Si/SiO₂ interface thermally grown in the temperature range T_ox = 400–1066 °C to assess interface quality in terms of inherently incorporated point defects. This reveals the presence predominantly of two species of a P_b-type interface defect (interfacial Si dangling bond), which, based on pertinent ESR parameters, is typified as P_b0⁽²¹¹⁾ variant, close to the P_b0 center observed in standard (100)Si/SiO₂—known as utmost detrimental interface trap. T_ox ≳ 750 °C is required to minimize the P_b0⁽²¹¹⁾ defect density (∼4.2 × 10¹²cm⁻²; optimized interface). The data clearly reflect the non-elemental nature of the (211)Si face as an average of (100) and (111) surfaces. It is found that in oxidizing (211)Si at T_ox ≳ 750 °C, the optimum Si/SiO₂ interface quality is retained for the two constituent low-index (100) and (111) faces separately, indicating firm anticipating power for higher-index Si/SiO₂ interfaces in general. It implies that, as a whole, the quality of a thermal higher-index Si/SiO₂ interface can never surmount that of the low-index (100)Si/SiO₂ structure.