A method of manufacturing a light-emitting device, including: providing a substrate structure including a base portion and wherein the base portion includes a surface; performing a patterning step to form a plurality of protrusions, wherein the plurality of protrusions are arranged on the surface of the base portion; forming a buffer layer on the surface of the base portion by physical vapor deposition, wherein the buffer layer covers the protrusions; and forming III-V compound semiconductor layers on the buffer layer; wherein one of the plurality of protrusions has a height not greater than 1.5 μm; and wherein the light-emitting device has a full width at half maximum (FWHM) of smaller than 250 arcsec in accordance with a (102) XRD rocking curve.