Electron spin resonance features of interface defects in thermal (100)Si/SiO2

Electron spin resonance (ESR) on thermal $\text{(100)}{\mathrm{Si/SiO}}_{\mathrm{2}}$ predominantly exhibiting either the $P_{\text{b0}}$ or $P_{\text{b1}}$ interface defect confirms the $P_{\text{b1}}$ point symmetry as monoclinic-$I$ with $g_1\text{=2.0058,}$ $g_2\text{=2.00\hspace{0.17em}735±0.00\hspace{0.17em}010,}$ and $g_3\text{=2.0022,}$ where the $g_2$ direction is at $\text{3°±1°}$ (towards the interface) with a 〈111〉 direction at 35.3° with the interface plane. Its line width is found weakly dependent on magnet angle, exhibiting a strain induced spread ${\sigma }_{g_{\perp }}\text{∼0.00\hspace{0.17em}035}$ in $g_{\perp }$ about 2–3 times less than typical for $P_b$ in $\text{(111)}{\mathrm{Si/SiO}}_{\mathrm{2}}.$ For $P_{\text{b0}},$ an axially symmetric $g$ matrix is observed, with $g_{\parallel }\text{=2.0018}$ and $g_{\perp }\text{=2.0081,}$ and ${\sigma }_{g_{\perp }}\text{∼0.0009.}$ From comparison of salient ESR data, it is concluded that $P_b$ and $P_{\text{b0}}$ are chemically identical; however, systematic fabrication-induced variations in defect environment will lead to second order systematic shifts in average properties. The $P_{\text{b1}}$ defect is provisionally pictured as an unpaired Si bond on a defect Si atom at slightly subinterface plane position in the Si substrate, possibly facing an oxygen atom.