In situ, real-time measurement of wing tilt during lateral epitaxial overgrowth of GaN

By performing in situ, real-time x-ray diffraction measurements in the meta lorganic chemical-vapor deposition environment, we have directly observed t he emergence and evolution of wing tilt that occurs during the lateral over growth of GaN from stripes patterned in a SiO2 mask. This was done by repea tedly performing line scans through the 10 (1) over bar 3 peak in the direc tion perpendicular to the [10 (1) over bar 0](GaN) stripe direction. The wi ng tilt developed as soon as the wings started forming, and increased sligh tly thereafter to reach a value of similar to 1.19 degrees after 3600 s of growth. Upon cooldown to room temperature, the tilt increased to similar to 1.36 degrees, indicating that thermally induced stresses during cooldown h ave only a small effect on wing tilt. However, changes in mask density, com position, and stress state during early lateral overgrowth must be consider ed as possible origins of wing tilt. (C) 2000 American Institute of Physics . [S0003-6951(00)02926-0].