Damage in Si induced by irradiation with various light/medium mass ions at elevated temperatures and high doses (у3ϫ10 16 cm Ϫ2 ) was studied using Rutherford backscattering spectroscopy, cross-section transmission electron microscopy, and high resolution x-ray diffraction. The results obtained have shown that there is a marked variation in the damage accumulation for different ion species. For O ϩ and N ϩ ions a distinct layer with a low level of damage presenting negative strain is formed at the surface. It has been found that the magnitude of the strain does not correlate with the energy deposited in the collision cascades. In the cases of Ne ϩ and Mg ϩ implantation, a low damage accumulation occurs near the surface but no negative strain is formed. In contrast to the N ϩ and O ϩ cases, with the increase of the Ne ϩ or Mg ϩ dose (Ͼ1ϫ10 17 cm Ϫ2 ) the damage profile stretches almost to the crystal surface. It is proposed that in addition to the mechanism of spatial separation of Frenkel pairs taking place in the collision cascades, the ability of the implanted ions to form precipitates and complexes with Si atoms noticeably influences the damage formation during implantation at elevated temperatures.

The accumulation of damage and the development of mechanical strain in crystalline Si ͑c-Si͒ by O and N ion implantation to doses up to 4ϫ10 17 cm Ϫ2 at elevated temperatures have been studied using Rutherford backscattering spectrometry and high resolution x-ray diffraction. The implantation of O or N ions at high temperatures produces two distinct layers in the implanted c-Si: ͑i͒ a practically damage-free layer extending from the surface up to Ӎ half of the depth of the mean projected range (R p ) and presenting negative strain ͑of contraction͒; and ͑ii͒ a heavily damaged layer located around and ahead of the R p with no significant strain. Both the damage distribution and the magnitude of the strain were found to be dependent on the ion species implanted. We proposed that besides the spatial separation of Frenkel pair defects due to the mechanics of the collision processes and the intensive dynamic annealing, an ion beam induced annealing process also participate in the formation of the near-surface damage-free layer during high temperature implantation of c-Si.

The development of mechanical strain and accumulation of damage in silicon single crystals implanted with Ne ions to doses in the range of 0.1-1.0 ϫ10 17 cm Ϫ2 at temperatures from 200 to 600°C were investigated employing Rutherford backscattering spectrometry, high resolution x-ray diffraction ͑HRXRD͒ analysis and cross section transmission electron microscopy ͑XTEM͒. Two distinct layers have been found in the implanted material: A near-surface layer (Ͻ 0.2 m thick͒ where no extended defects are observed and a buried layer (Ϸ0.5 m thick͒ containing a dense array of dislocation loops and defect clusters. XTEM analysis revealed a distribution of small spherical cavities presumably filled with Ne, with a diameter Ͻ4 nm, extending along the entire depth of the implanted layer. HRXRD studies showed the presence of a positive strain ͑of expansion͒, irrespective of the implanted dose and temperature. The findings are discussed in terms of the proposed model which assumes that vacancy-type defects are consumed during the formation of Ne bubbles.

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In this paper we discuss the structural modifications observed in a buried amorphous Si (a-Si) layer containing high oxygen concentration level ͑up to ϳ3 at. %͒ after being implanted at elevated temperature with 16 O ϩ ions. For implants conducted at temperatures lower than 150°C, the a-Si layer expands via layer by layer amorphization at the front and back amorphous-crystalline ͑a-c͒ interfaces. When performed at temperatures above 150°C, the implants lead to the narrowing of the buried a-Si layer through ion beam-induced epitaxial crystallization at both a-c interfaces. Cross section transmission electron microscopy analysis of samples implanted at 400°C revealed an array of microtwins and a dislocation network band in the recrystallized material. In samples implanted at 550°C, only a buried dislocation network band is observed.