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At least 343 records · Page 19

Activation of ion-implanted polycrystalline silicon thin films prepared on glass substrates

Phosphorous-implanted polycrystalline Si thin films were subjected to thermal annealing between 300 °C and 650 °C. The thermal activation was monitored electrically and structurally using Hall measurements, Raman spectroscopy, UV–visible spectrophotometry, and transmission electron microscopy. Charge transport information was correlated to the corresponding structural evolution in thermal activation. Phosphorous-implanted activation is divided into short-range ordering at low temperatures and long-range ordering at high temperatures, with the boundary between low and high temperatures set at 425 °C. Short-range ordering allows for significant increase in electronic concentration through substitution of P for Si. Higher temperatures are attributed to long-range ordering, thereby increasing electronic mobility.

36 MATERIALS SCIENCE↗

Interaction of Sn atoms with defects introduced by ion implantation in Ge substrate

The interaction of Sn atoms with defects induced by Sn implantation of Ge substrates with antimony (Sb) as an n-type dopant and the impact of H{sub 2} annealing on these defects were investigated by comparison with defects induced by Ge self-implantation. In the Ge samples implanted with either Sn or Ge, and annealed at temperatures of less than 200 °C, divacancies, Sb-vacancy complexes with single or double acceptor-like states, and defects related to Sb and interstitial Ge atoms were present. On the other hand, after annealing at 500 °C in an N{sub 2} or H{sub 2} atmosphere, defects with different structures were observed in the Sn-implanted samples by deep level transition spectroscopy. The energy levels of the defects were 0.33 eV from the conduction band minimum and 0.55 eV from the valence band maximum. From the capacitance-voltage (C-V) characteristics, interaction between Sn atoms and defects after annealing at 500 °C was observed. The effect of H{sub 2} annealing at around 200 °C was observed in the C-V characteristics, which can be attributed to hydrogen passivation, and this effect was observed in both the Ge- and Sn-implanted samples. These results suggest the presence of defects that interact with Sn or hydrogen atoms. This indicates the possibility of defect control in Ge substrates by Sn or hydrogen incorporation. Such defect control could yield high-performance Ge-based devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗