Low-temperature growth of gallium nitride films by inductively coupled-plasma-enhanced reactive magnetron sputtering

Gallium nitride (GaN) films were grown on sapphire substrate by reactive magnetron sputtering. Inductively coupled-plasma (ICP) source was installed between the substrate holder and the sputtering target to increase the plasma density and the degree of ionization of nitrogen gas. Liquid Ga and Ar/N ₂ were used as the sputtering target and sputtering gases, respectively. X-ray diffraction measurements confirmed that the authors could grow high quality GaN crystallites at 500°C. However, the crystalline GaN (0002) peak remained even by lowering the growth temperature down to 300°C. The N:Ga ratio of the film grown at 500°C was almost 1:1, and the nitrogen composition became higher toward the 1:1 N:Ga ratio with increasing the growth temperature. The high degree of ionization induced by ICP source was essential to the growth of high crystalline quality GaN films.