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 metalorganic chemical-vapor deposition environment, we have directly observed the emergence and evolution of wing tilt that occurs during the lateral overgrowth of GaN from stripes patterned in a SiO2 mask. This was done by repeatedly performing line scans through the 10 (1) over bar 3 peak in the direction perpendicular to the [10 (1) over bar 0](GaN) stripe direction. The wing tilt developed as soon as the wings started forming, and increased slightly 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 have only a small effect on wing tilt. However, changes in mask density, composition, and stress state during early lateral overgrowth must be considered as possible origins of wing tilt. (C) 2000 American Institute of Physics. [S0003-6951(00)02926-0].