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AFM images of lines in 0.4 Ω cm p-type type silicon irradiated with 34 keV He ions with a period of 700 nm, with (a) Ψ = 6 × 107/cm, (b)3 × 108/cm, (c) 6 × 108/cm. (d) Period of 5 μm for Ψ = 2 × 1010/cm. After anodization, oxidation at 800 °C for 20 min and immersion in a 2% HF solution is used to remove oxidised porous silicon.
(a) Cross-section SEM showing lines irradiated with 500 keV protons with different Ψ in 0.4 Ω cm silicon, anodized with a current density of 40 mA/cm2 to a depth of 30 μm. A higher magnification of the lowest Ψ is shown at the left. (b) Optical and (c) PL images of the same lines. PL was excited using a wavelength of 330 to 380 nm and the image was collected for 50 ms. The insets in (c) show PL intensity across the lowest and highest Ψ cores.
Cross-section (a) optical and (b), (c) SEM images of irradiated 0.02Ω cm p-type silicon cleaved for imaging: (a) irradiated with 2 MeV proton Ψ = 1.6 × 1011/cm, then anodized to a depth of 50 μm; (b) irradiated with 2 MeV proton Ψ = 2 × 1012/cm, then anodized to a depth of 60 μm; (c)10 μm irradiated width with 1 MeV proton Ψ = 1 × 1015/cm2, then anodized to a depth of 30 μm.
(a) SRIM map of the average vacancy distribution vG(x, y) (μm−2) per 30 keV He+ in silicon. (b) (μm−3) map for Ψ = 4 × 108/cm in 0.4 Ω cm silicon. (c) Electric potential map for Ψ = 1 × 107/cm. (a)–(c) have a vertical box size of 0.5 μm. (d) Potential (color scale on the right) and current streamlines for (upper) drift component and (lower) total current flow for increasing values of Ψ. The horizontal × vertical box size is 3 × 2 μm2. (e) Hole density and (f) total current density versus depth at the symmetry axis, for different Ψ. The legend in the centre is common to both.
Simulations for 250 keV proton line irradiation in 0.4 Ω cm silicon, (a) Ψ = 1010/cm, (b) Ψ = 1011/cm, showing potential maps with superposed hole current streamlines; arrows indicate direction of the electric field (the arrow length is normalized, so not proportional to the field strength). The horizontal × vertical box size is 4 × 4 μm2.
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