A high luminance semiconductor light emitting device including a metallic reflecting layer formed using a non-transparent semiconductor substrate is provided. The device includes a GaAs substrate; a metal layer disposed on the GaAs substrate; and a light emitting diode structure. The light emitting diode structure includes a patterned metal contact layer and a patterned insulating layer disposed on the metal layer, a p type cladding layer disposed on the patterned metal contact layer and the patterned insulating layer, a multi-quantum well layer disposed on the p type cladding layer, an n type cladding layer disposed on the multi-quantum well layer, and a window layer disposed on the n type cladding layer. The GaAs substrate and the light emitting diode structure are bonded by using the metal layer.