US Patent 7518151 Gallium nitride/sapphire thin film having reduced bending deformation

The present invention relates to a gallium nitride/sapphire thin film, wherein a curvature radius thereof is positioned on the right side of a curve plotted from the following functional formula (I):Y=Y0+A·e−(x1−1)/T1+B·(1−e−x2/T2)  (I)whereinY is the curvature radius (m) of a gallium nitride/sapphire thin film,x1 is the thickness (μm) of a gallium nitride layer,x2 is the thickness (mm) of a sapphire substrate,Y0 is −107±2.5,A is 24.13±0.50,B is 141±4.5,T1 is 0.56±0.04, andT2 is 0.265±0.5.