The present disclosure provides a light-emitting device comprising a substrate with a topmost surface; a first semiconductor stack arranged on the substrate, and comprising a first top surface separated from the topmost surface by a first distance; a first bonding layer arranged between the substrate and the first semiconductor stack; a second semiconductor stack arranged on the substrate, and comprising a second top surface separated from the topmost surface by a second distance which is different form the first distance; a second bonding layer arranged between the substrate and the second semiconductor stack; a third semiconductor stack arranged on the substrate, and comprising third top surface separated from the topmost surface by a third distance; and a third bonding layer arranged between the substrate and the third semiconductor stack; wherein the first semiconductor stack, the second semiconductor stack, and the third semiconductor stack are configured to emit different color lights.