Misfit point defects at the epitaxial $Lu2O3/(111)Si$ interface revealed by electron spin resonance

Electron spin resonance study on heteroepitaxial Si/insulator structures obtained through the growth of epi-$Lu2O3$ films on (111)Si (⁠$∼4.5$ % mismatched) by reactive molecular beam epitaxy indicates the presence in the as-grown state of interfacial $Pb$ defects $(∼5×1011cm−2)$ with an unpaired $sp3$ Si dangling bond (DB) along the [111] sample normal, prototypical of the standard thermal $(111)Si/SiO2$ interface. The defects, with density remaining unchanged to anneal in vacuum up to temperatures of $Tan∼420°C$⁠, directly reveal the nonperfect pseudoepitaxial nature of the interface, laid down in electrically detrimental interface traps. These are suggested to be interfacial Si DBs related to Si misfit dislocations. Alarmingly, defect passivation by standard anneal treatments in $H2$ fall short. For higher $Tan$⁠, the interface deteriorates to “standard” $Si/SiO2$ properties, with an attendant appearance of EX centers indicating $SiO2$ growth. Above $Tan∼1000°C$⁠, the interface disintegrates altogether.