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 P_b defects (∼5×10¹¹ cm^-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 T_an∼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 T_an, the interface deteriorates to “standard” Si/SiO₂ properties, with an attendant appearance of EX centers indicating SiO₂ growth. Above T_an∼1000 °C, the interface disintegrates altogether.