Improvement on epitaxial grown of InN by migration enhanced epitaxy

Epitaxial growth of InN on (0001) sapphire with an AlN buffer layer was studied by migration-enhanced epitaxy, which is composed of an alternative supply 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-grown films were characterized by x-ray diffraction (XRD), reflective high-energy electron diffraction, atomic-force microscopy (AFM), and Hall measurements. Both XRD theta-2 theta and omega scans show that the full width at half maximum of the (0002) peak nearly continuously decrease with increasing growth temperature, while InN grown at 590 degrees C shows the poorest surface morphology from AFM. It is suggested that three-dimensional characterization is necessary for an accurate evaluation of the quality of the InN epilayer. 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 nitrogen vacancies are responsible for the high background n-type conductivity of InN. To illuminate the relationship between Hall mobility and carrier concentration, the electrical properties of all InN films grown recently were summarized. (C) 2000 American Institute of Physics. [S0003-6951(00)00942-6].