Transient characteristics of isoelectronic bound excitons at hole-attractive defects in silicon: The C(0.79 eV), P(0.767 eV), and H(0.926 eV) lines

Highly enriched Si28 reveals remarkable optical linewidths and fine structure for well-known damage centers

“…In a study of the transient decay of the C center PL, Bohnert et al [18] inferred that the observed NP C-line must originate from the singlet IBE state, and that there must be an unobserved triplet level lying ∼3.2 meV below the singlet level. This was confirmed later by the observation of PL from the triplet level (labelled C T ) lying 2.64 meV below the singlet transition (now labelled C 0 ) [33].…”

“…Here we report on optical emission and absorption studies on three well-known damage centers produced in very high purity Si enriched to 99.995% 28 Si as part of the Avogadro project [12]. All three emit in or near important optical communication bands: the C center (790 meV, or 1571 nm, thought to contain an interstitial C (C i ) and an interstitial O (O i ) [13][14][15][16][17][18]), the G center (969 meV, or 1280 nm, thought to contain a substitutional C (C s ), C i , and an interstitial Si (Si i ) [4,15,19,20]), and the W center (1019 meV, or 1217 nm, thought to consist of three Si i [21][22][23]). All three produce strong photoluminescence (PL) in 28 Si irradiated with 10 MeV electrons, and the G center also has relatively strong absorption transitions.…”

“…No-phonon C0 photoluminescence in28 Si irradiated with 32 kGy and annealed at 250 • C. (Top left inset) Energy diagram showing the singlet and triplet bound exciton levels giving rise to the C0 and CT lines. (Other insets) The CT line and the isotopically shifted C0 lines resulting from naturally abundant18 O and 13 C isotopes, with the same, but shifted, energy scale as the mainfigure.Relative to a normalized C0-line, the amplitudes of the CT,18 O and 13 C intensities are 0.0079, 0.0050 and 0.0267. Collected at 4.2 K using 0.62 µeV resolution, with the linewidths dominated by the instrumental contribution.…”

Lattice isotope effects on optical transitions in silicon

“…The Si sample used in this work was isotopically enriched Czochralski 30 Si with abundances 28 Si ͑0.67%͒, 29 Si ͑0.59%͒, and 30 Si ͑98.74%͒, giving a mean mass number of M ͑ 30 Si͒ = 29.98. The sample contained substitutional carbon at a concentration of ͓C͔Ϸ10 17 cm −3 , interstitial oxygen at ͓O͔ = 8.8ϫ 10 17 cm −3 , and substitutional boron at ͓B͔ = 5.5 ϫ 10 16 cm −3 .…”

“…Then, we can take the measured data for the temperature dependence of the energy of the "C" line, remove the lattice expansion contribution, and scale the remainder to the electron-phonon coupling term in the indirect energy gap. The "C" line has a very low oscillator strength 8,29 making absorption measurements difficult, and in PL it is thermally quenched, restricting measurements to T Ͻ 80 K. 23 The measured shift between 0 and 80 K is −1.52± 0.08 meV (see Fig. 4).…”