Observation and electronic characterization of two E′ center charge traps in conventionally processed thermal SiO2 on Si

Abstract

We demonstrate that at least two varieties of E′ defect precursors exist in a wide variety of conventionally processed thermal SiO2 thin films. We provisionally label the defects EP and E′γp. We find that EP defect capture cross sections exceed the corresponding E′γp values by an order of magnitude, that EP centers are distributed far more broadly throughout the oxides than are the E′γp defects, and that the EP resonance, unlike the E′γp resonance is not stable at room temperature.

Characterization ofE′δand triplet point defects in oxygen-deficient amorphous silicon dioxide

“…[5][6][7][8][9][10][11] However, a definitive attribution of the microscopic model for the E' γ is still lacking since a correlation with the precursor defect, the oxygen vacancy, has not yet been clearly posed and other precursors have also been suggested. 1,2 The E' δ center has been observed in bulk a-SiO 2 [12][13][14] and in a-SiO 2 layers [15][16][17][18][19][20][21] on silicon. Its EPR resonance line is nearly isotropic (g∼2.002) and together with this signal a pair of lines split by ∼10 mT, supposed to arise from hyperfine interaction of the unpaired electron with a 29 Si nucleus, is usually detected.…”

“…1, and fixing g  =2.0018 for E' γ , 1 a zero crossing g value of 2.0020±0.0001 has been obtained for E' δ center, in good agreement with other experimental estimations. 12,15,16,[18][19][20] The line shapes reported in Fig. 1(b) and 1(c) were also used to estimate the concentrations of E' γ and E' δ induced in other samples of Pursil 453 irradiated to different gamma ray doses.…”

“…16,18,19 In this respect the thermally induced E' γ center could be considered the direct analogous in a-SiO 2 of the E' 1 center of quartz. In more details, the E' γ center induced during annealing should originate from an oxygen vacancy that, by trapping an hole, becomes paramagnetic, as well as the E' 1 .…”

Delocalized Nature of theEδ′Center in Amorphous Silicon Dioxide

“…The intensity ratio ζ between the 10 mT hyperfine doublet and the E' δ main EPR line is ζ∼0. 16. This is the consequence of the existence of four nearly equivalent sites of the defect in which the 29 Si can be localized.…”

“…The E' δ center was observed in X-ray and γ-ray irradiated bulk SiO 2 [12][13][14], in thermally grown thin SiO 2 films upon annealing [15][16][17][18], and in buried oxide layers obtained by oxygen implantation (SIMOX) [19][20]. The principal EPR characteristics of this center are a main resonance line showing nearly isotropic g tensor (g∼2.002) and a pair of line with separation of ∼10 mT, supposed to arise from hyperfine interaction of the unpaired electron with a 29 Si nucleus (I=1/2) [12,14].…”