Nature and stability of the (100)Si/LaAlO₃ interface probed by paramagnetic defects

Electron spin resonance analysis of (100)Si/LaAlO₃ structures reveals the absence of a Si/SiO₂-type interface in terms of archetypal Si-dangling bond-type Si/SiO₂ interface defects (P_b0,P_b1). With no P_b-type defects observed, this state is found to persist during subsequent annealing (5% O₂+N₂ ambient) up to T_an∼800 °C, indicating a thermally stable and abrupt Si/LaAlO₃ interface. In the range T_an∼800–860 °C, however, a Si/SiO₂-type interface starts forming as evidenced by the appearance of P_b0 defects and, with some delay in T_an, the EX center (a SiO₂ associated defect) attesting to significant structural/compositional modification. The peaking of the defect density versus T_an curves indicates that the interlayer with SiO_x nature breaks up upon annealing at T_an≥930 °C, possibly related to crystallization and silicate formation. No LaAlO₃-specific point- - defects could be detected.