High-resolution absorption spectroscopy of the deep impurities S and Se inS28irevealing theS

Host isotope mass effects on the hyperfine interaction of group-V donors in silicon

“…Each of the hyperfine-split 31 P, 75 As, 121 Sb, 123 Sb, and 209 Bi ENDOR lines splits further into multiple components, whose relative intensities accurately match the statistical likelihood of the nine possible average Si masses in the four nearest-neighbor sites due to random occupation by the three stable isotopes 28 Si, 29 Si, and 30 Si. Further investigation with 31 P donors shows that the resolved ENDOR components shift linearly with the bulk-averaged Si mass.…”

“…If a well-defined resonance frequency is needed across the spin ensemble, one should employ monoisotopic 28 Si or 30 Si crystals but not the magnetic 29 Si to avoid decoherence. On the other hand, a mixture of 28 Si and 30 Si may provide a frequency-wise addressability to multiple donor nuclear spins placed in different Si mass surroundings. Table I lists the host isotope composition f and the bulk-averaged isotope mass M bulk of the phosphorusdoped single-crystal Si samples used in the ENDOR experiments.…”

“…We also exclude the "magnetic" host isotope effect due to 29 Si nuclear spins since, as seen in Fig. 2(d), sample G that has the largest mass-disorder with non-magnetic 28 Si and 30 Si with a relatively small amount of magnetic 29 Si shows the largest degree of splitting spanning L = 0 to 8. Indeed, as we will show below, the following equation including the mass effects only is found to describe the experimentally observed host isotope effects on the donor dependent hyperfine parameter: …”

“…Elimination of the host 29 Si nuclear magnetic moments by nuclear-spin-free 28 Si isotopic enrichment led to spectral narrowing of phosphorus donor electron spin resonance (ESR) lines [5][6][7] and the coherence time extension of phosphorus electron spins 5,8 and nuclear spins. [9][10][11] The effects of host silicon isotopes ( 28 Si, 29 Si, 30 Si) are well known in a variety of impurity electric dipole transitions in silicon. [12][13][14][15][16] While the host isotope "magnetic" effects, e.g., super-hyperfine interaction of donor electron spins in silicon with surrounding 29 Si nuclear spins have been investigated extensively by electron-nuclear double resonance (ENDOR), 17,18 previous reports on the host isotope "mass" effects on impurity magnetic resonance in silicon are rather limited.…”

Competition between homogeneous and inhomogeneous broadening of orbital transitions in Si:Bi

“…The isotopic composition primarily affects the ground state. The nearest neighbor (NN) Si isotope arrangement produces discrete states, which are clearest in the chalcogen donors 24,25 , where the total mass in the four NNs produces a significant shift in the energy. The isotopic randomness beyond the NN shell is responsible for the inhomogeneous broadening.…”