15 January 2013
Publication year: 2013
Source:Journal of Crystal Growth, Volume 363
Strain evolution in GaN layers grown on flat (FSS) and cone shaped patterned sapphire substrates (CPSS) is studied by in-situ reflectance and curvature measurements. Intrinsic growth strain and dislocation density are investigated in relation to different steps of the growth procedure. In spite of the typical tensile strain of GaN on sapphire, a clear compressive stress during growth is found when the lateral coalescence time is delayed. From the curvature measurement, the average compressive stress during GaN layer growth on CPSS before full coalescence is determined to be below 0.21
► Strain evolution in GaN growth on patterned sapphire is studied. ► In-situ curvature measurements help to understand the strain state during growth. ► Compressive stress during growth is found when the lateral coalescence time is delayed. ► The reasons of compressive strain during growth are ascribed to capillarity effects and tilted sidewalls on CPSS. ► Optimized growth procedures enable nearly zero wafer bow in critical growth steps of LEDs.
Publication year: 2013
Source:Journal of Crystal Growth, Volume 363