A study of Cu metal deposition on amorphous Si films from Cu solutions for low-temperature crystallization of amorphous Si films

Discrete copper metal particles were deposited on amorphous Si films by the spin-coating of Gu solutions, and they were utilized as surface nucleation sites for solid-phase crystallization of the amorphous Si films. About 99% of the as-deposited Cu metal particles from the 1000 ppm Cu solution were evaporated, and the residual Cu particles migrated to form metal clusters after annealing at 530 degrees C for 10 min. The clusters acted as surface nucleation sites which caused a fractal growth with the shape of tree branches. The crystallization temperature of the amorphous Si films with Cu metal particles on them was much lower than that of a-Si films without Cu metal. When the Cu concentration in the solution was above 100 ppm, the crystallization was generally enhanced with the increase in the Cu concentration. However, the amorphous Si film spin-coated with 10 ppm solution crystallized faster than the a-Si film with 100 ppm, because the increased pH in the Cu solution enhanced the deposition of Cu metal particles. The amount of the as-deposited Cu atoms with 100 ppm Cu solution had a minimum value of 5 x 10(13) atom cm(-3). The crystalline fraction by annealing at 530 degrees C for 20 h was proportional to the amount of the as-deposited Cu metal, instead of the Cu concentration in solution.