Improvement on epitaxial grown of InN by migration enhanced epitaxy

Epitaxial growth of InN on (0001) sapphire with an AlN buffer layer was stu died by migration-enhanced epitaxy, which is composed of an alternative sup ply of pure In atoms and N-2 plasma. A series of samples were prepared with different substrate temperatures ranging from 360 to 590 degrees C. As-gro wn films were characterized by x-ray diffraction (XRD), reflective high-ene rgy electron diffraction, atomic-force microscopy (AFM), and Hall measureme nts. Both XRD theta-2 theta and omega scans show that the full width at hal f maximum of the (0002) peak nearly continuously decrease with increasing g rowth temperature, while InN grown at 590 degrees C shows the poorest surfa ce morphology from AFM. It is suggested that three-dimensional characteriza tion is necessary for an accurate evaluation of the quality of the InN epil ayer. Hall mobility as high as 542 cm(2)/V s was achieved on film grown at similar to 500 degrees C with an electron concentration of 3x10(18) cm(-3) at room temperature. These results argue against the common view that nitro gen vacancies are responsible for the high background n-type conductivity o f InN. To illuminate the relationship between Hall mobility and carrier con centration, the electrical properties of all InN films grown recently were summarized. (C) 2000 American Institute of Physics. [S0003-6951(00)00942-6] .