SI-DOPED AND GE-DOPED GAN FILMS GROWN WITH GAN BUFFER LAYERS

Si- and Ge-doped GaN films were grown with GaN buffer layers. Si-doped GaN films, of which the carrier concentration was as high as 2 x 10(19)/cm3, were obtained. Every Si-doped GaN film showed a surface morphology that was smooth and mirrorlike. Ge-doped GaN films, of which the carrier concentration was as high as 1 X 10(19)/cm3, were obtained. Surface morphology of Ge-doped GaN films became poor around this carrier concentration. Both dopings showed good linearity of the carrier concentration as a function of the flow rate of GeH4 and SiH4. Therefore, Ge and Si are suitable n-type dopants for GaN.