Positron trapping at divacancies in thin polycrystalline CdTe films deposited on glass

Abstract

We have performed positron annihilation experiments on CdTe films grown by vacuum evaporation at 220 °C on both plain glass and indium-tin-oxide-coated glass substrates. By checking the linearity of the valence annihilation parameter S versus the core annihilation parameter W we introduce a method to analyze the data which directly shows that the same vacancy defect can be present in all the films. By comparing the core annihilation parameter at the defect to that at the VCd vacancy we can identify this defect as the divacancy VCd-VTe. Its concentration in the films decreases from about 1018 to less than 1016 cm−3 after annealing in air at 400 °C for about 30 min. Chlorine doping seems to stabilize the divacancies.

Optimal conditions forNV−center formation in type-1b diamond studied using photoluminescence and positron annihilation spectroscopies

“…For fluences ≥ 5 × 10 14 cm −2 the (S, W ) points are located above D1, indicating that a new type of vacancyrelated defect appears 19 . This claim is supported by the fact that we measure larger relative changes of S values than the one of the neutral or negative monovacancy in diamond 18 (S V • /S L = 1.08 ± 0.01 and S V − /S L = 1.079 ± 0.002) indicated by the horizontal black line in Fig.…”

Positron annihilation and constant photocurrent method measurements on a-Si:H films: A comparative approach to defect identification

“…The low-momentum fraction, S, depends primarily on size and concentration of open volume defects, whereas the high-momentum fraction, W, is sensitive to the electronic structure at the annihilation site. Together, these two parameters form a unique signature for different defect structures (Liszkay et al, 1994).…”

Study of multiblock polyamide-6/Poly-(isoprene) copolymers by positron annihilation spectroscopy

“…As seen, all experimental points lie in the error limits on the line, whereas the two experimental points, due to the samples №1 and №5 are close, but not on the same line. The common explanation of linear S-W plot [19] observed in some cases when several types of defects exist in the samples studied [20]. In M. Misheva et al [21] the experimental points that refer to samples with different microstructures lie on different straight lines.…”