STUDY OF SURFACE CRYSTALLINITY AND STOICHIOMETRY OF LASER-ANNEALED GAAS USING TIME-RESOLVED REFLECTIVITY AND CHANNELING

The surface crystallinity and stoichiometry of tellurium-implanted GaAs annealed with a frequency-doubled Nd:glass laser using time-resolved reflectivity and channeling measurements has been studied. By optimizing the duration of the liquid melt, depending on the implant dose, it has been possible to laser anneal implanted layers in uncapped GaAs with good surface crystallinity and minimal loss of arsenic due to surface decomposition. We propose a qualitative model of arsenic evaporation at the surface and subsequent replacement by arsenic displaced from the bulk by the tellurium which explains the dependence of the optimum melt duration on the dose of the implant.