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 $(Pb0,Pb1)$⁠. With no $Pb$-type defects observed, this state is found to persist during subsequent annealing (5% $O2+N2$ ambient) up to $Tan∼800°C$⁠, indicating a thermally stable and abrupt $Si∕LaAlO3$ interface. In the range $Tan∼800–860°C$⁠, however, a $Si∕SiO2$-type interface starts forming as evidenced by the appearance of $Pb0$ defects and, with some delay in $Tan$⁠, the $EX$ center (a $SiO2$ associated defect) attesting to significant structural/compositional modification. The peaking of the defect density versus $Tan$ curves indicates that the interlayer with $SiOx$ nature breaks up upon annealing at $Tan⩾930°C$⁠, possibly related to crystallization and silicate formation. No $LaAlO3$-specific point defects could be detected.