The role of high-temperature island coalescence in the development of stresses in GaN films

The formation of dislocations and stress in GaN layers grown by metalorganic vapor phase epitaxy on sapphire is investigated with regard to the average grain diameter. The grain diameter was determined by monitoring the high-temperature GaN island coalescence process during growth using reflectometry. It is found that the density of edge threading dislocations decreases and the compressive stress measured after cooling to room temperature increases when the coalescence thickness and the grain diameter increase. The data are consistent with models of development of tensile stress due to island coalescence during growth.

[1]  Sven Einfeldt,et al.  In situ and ex situ evaluation of the film coalescence for GaN growth on GaN nucleation layers , 2000 .

[2]  Alan Francis Wright,et al.  Elastic properties of zinc-blende and wurtzite AlN, GaN, and InN , 1997 .

[3]  X. H. Wu,et al.  Dislocation generation in GaN heteroepitaxy , 1998 .

[4]  Reinhold Koch,et al.  The intrinsic stress of polycrystalline and epitaxial thin metal films , 1994 .

[5]  S. Einfeldt,et al.  Analysis of the Defect Structure of Epitaxial GaN , 1999 .

[6]  R. W. Hoffman,et al.  Stress Anisotropy in Evaporated Iron Films , 1959 .

[7]  Sven Einfeldt,et al.  X-ray diffraction analysis of the defect structure in epitaxial GaN , 2000 .

[8]  H. Amano,et al.  Effects of the buffer layer in metalorganic vapour phase epitaxy of GaN on sapphire substrate , 1988 .

[9]  C. T. Foxon,et al.  Lattice parameters of gallium nitride , 1996 .

[10]  Y. S. Touloukian.  Thermal Expansion: Nonmetallic Solids , 1977 .

[11]  R. K. Kirby,et al.  Numerical Data on Thermal Linear Expansion of Nonmetallic Solids , 1977 .

[12]  R. Reeber,et al.  Thermal Expansion Of GaN And Ain , 1997 .

[13]  J. Cohen,et al.  Diff raction f rom Materials , 2006 .

[14]  Hadis Morkoç,et al.  Mosaic growth of GaN on (0001) sapphire: A high-resolution electron microscopy and crystallographic study of threading dislocations from low-angle to high-angle grain boundaries , 2000 .

[15]  Jung Han,et al.  Stress evolution during metalorganic chemical vapor deposition of GaN , 1999 .

[16]  S. Denbaars,et al.  The Effect of Growth Environment on the Morphological and Extended Defect Evolution in GaN Grown by Metalorganic Chemical Vapor Deposition , 1998 .

[17]  S. Einfeldt,et al.  Strain relaxation in AlGaN under tensile plane stress , 2000 .

[18]  Oliver Ambacher,et al.  Defect structure of epitaxial GaN films determined by transmission electron microscopy and triple-axis X-ray diffractometry , 1998 .

[19]  Detlef Hommel,et al.  Thermal expansion of bulk and homoepitaxial GaN , 2000 .

[20]  Isamu Akasaki,et al.  Quantum-Confined Stark Effect due to Piezoelectric Fields in GaInN Strained Quantum Wells , 1997 .