Interface traps and <i>P</i> <i>b</i> centers in oxidized (100) silicon wafers

Abstract

The band-gap energy distribution of Pb centers on oxidized (100) Si wafers has been determined and compared with interface electrical trap density Dit. Two different Pb centers are observed on (100) Si: Pb0, which has the structure ⋅Si≡Si3, and is essentially identical to the sole Pb center observed on (111) Si; and Pb1, of presently uncertain identity, but clearly different in nature from Pb0. By electric field-controlled electron paramagnetic resonance (EPR) and capacitance-voltage (C-V) measurements, it is found that Pb0 has its (0↔1) electron transition at Ev+0.3 eV and its (1↔2) transition at Ev+0.85 eV. Similarly, Pb1 has its (0↔1) transition at Ev+0.45 eV and its (1↔2) transition at Ev+0.8 eV. The Pb band-gap density correlates qualitatively and quantitatively with the electrical trap density Dit from C-V analysis; nonbonded Pb orbitals are found to be the source of about 50% of the characteristic traps in dry-oxidized, unannealed (100) Si wafers.