Electron spin resonance observation of Si dangling-bond-type defects at the interface of (100) Si with ultrathin layers of SiOx, Al2O3and ZrO2

Paramagnetic point defects were probed by electron spin resonance in stacks of (100) Si with nm-thin SiO x , ZrO 2 and Al 2 O 3 layers. After photodesorption of passivating hydrogen (300 K; 8.48 eV), the Si dangling bond type interface centres P bo , P b 1 appear as prominent defects at all (100) Si/dielectric interfaces, with P bo densities up to ~6 × 10 12 cm -2 . This P bo , P b 1 fingerprint, generally unique for the thermal (100) Si/SiO 2 interface, indicates that, while reassuring for the Si/SiO x /ZrO 2 case, the as-deposited (100)Si/Al 2 O 3 interface is basically Si/SiO 2 -like. As probed by the P b -type defects, the interfaces are under substantially enhanced stress, characteristic for low-temperature Si/SiO 2 growth. Standard quality thermal Si/SiO 2 interface properties, as exposed by the P b -type defects (density ~1 × 10 12 cm -2 ), may be approached by appropriate mild annealing (~650 °C). This fact of a naturally present or possibility to establish a high quality (100) Si/SiO 2 -type interface, with ultrathin SiO 2 interlayer, may be basic to successful application of high-κ metal oxides in Si-based devices.