Depth Distribution of Implanted Oxygen in Gallium Phosphide Measured by Nuclear Reaction Techniques

Abstract

The depth distribution of ion implanted 18 O in gallium phosphide has been measured by use of the nuclear reaction 18 O(p,α) 15 N which has a sharp resonance at a proton energy of 639 keV. Implantation energies of 20, 40, and 60 keV were used and average concentrations were achieved of as high as 3 × 10 21 ions/cm 3 over the implanted depths. Post-annealing of the 20 keV implant at 600 °C caused a slight broadening of the distribution.A mathematical treatment is given whereby the 18 O depth distribution can be derived from the experimental observation of the α-particle counting rate as a function of proton energy. This treatment involves a novel method of obtaining a smooth fit for the depth profile.Comparison of the smoothed experimentally measured distribution profiles with theoretical range distributions shows a reasonable fit, indicating that the projected ranges and distributions of oxygen implanted into GaP may be calculated with a fair degree of accuracy.