Microstructure and texture developments in multiple pulses excimer laser crystallization of GaAs thin films

Abstract

In this paper, we observed and characterized changes in the microstructure and texture during recrystallization and grain growth in polycrystalline GaAs thin films using multiple pulses crystallization by a KrF excimer laser. Films of various thicknesses were studied to assess film thickness and laser energy density effects. In the low temperature domain corresponding to the partial melting regime, normal grain growth was observed. In the superlateral grain growth regime the increase in grain size was notable with grain sizes much greater than the film thickness. A bimodal grain size distribution emerged implying the onset of secondary grain growth. The change in grain size distribution, texture, and grain boundary texture were analyzed using scanning electron microscopy and electron backscatter diffraction. It was found that grain growth is accompanied by a strengthening in {001} texture, indicating that the grain growth phenomenon is strain energy driven. The experimental results are explained with theory of secondary grain growth in thin films.