Dechanneling due to light ion microbeam induced swelling in single crystals

Abstract

Beam induced swelling can be the most significant cause of dechanneling for He+ and H+ microprobe measurements of the crystallinity of single crystals for irradiated regions of sizes typical of microprobe scans (∼ 100×100 μm2). Swelling causes dechanneling by tilting the crystal axis at the edge of the irradiated region. The present work shows that this effect only becomes significant, relative to dechanneling from beam induced point defects, above a threshold dose, Ds. For 2 MeV He+ incident along the axis of Si, Ds is ∼ 2×1017/cm2 and Ds is ∼ 4×1017/cm2 for GaAs. Since swelling induced dechanneling is confined to the edge of the irradiated area, increasing the beam scan size is a useful m..