Depth-selective defect analysis of Si implanted with As+ under channeling conditions using a variable-energy positron beam

Wafers of p-type Si (100) were implanted with 200 keV As+ ions with a dose of 1 x 10(13) ions/cm(2) from different directions, and Doppler broadening of positron annihilation gamma-rays was measured as a function of incident positron energy. The measurements were carried out to study the channeling effect of implanted ions on defect formation. The optimum defect distribution obtained from the positron data revealed that the defects produced by ion implantation under a channeling condition extended deeper than in the case without channeling. It was found that the channeling effect was significant when the implantation angle, defined as the angle between the direction of the ion beam and that normal to the (100) plane, was smaller than 3 degrees. (C) 1998 Elsevier Science B.V.