Pulsed UV laser irradiation effect for Sn⁺-implanted GaAs

Abstract

The effect of pulsed UV laser irradiation on Sn⁺-implanted GaAs was investigated systematically by combining RBS, SIMS and Raman scattering characterization techniques. Implantation energies and doses were controlled so as to realize a flat doping profile about 800 Å thick to a dose from 10¹⁷ to 10²¹ cm⁻³. An ArF excimer laser (λ = 193 nm) was used for the irradiation with a single pulse (∼20 ns) in the energy density range from 200 to 1400 mJ/cm². Strong segregation of Sn atoms toward the surface and partial movement of Sn atoms from an interstitial lattice site to substitutional sites were observed after the irradiation. Ordering of the disordered lattice was observed to proceed in the direction from the surface into the bulk in the same crystal orientation as the underlying layer. The behavior of Raman scattering spectra as a function of laser energy density was analyzed quantitatively based on a “spatial correlation” model. The analysis makes it possible to estimate an average particle size for the annealed crystal region in samples irradiated with a given energy density.