A light-emitting device, comprising: a support structure comprising a coating layer; a semiconductor structure disposed on the support structure, the semiconductor structure including a p-type semiconductor layer, an active layer and an n-type semiconductor layer from which an epitaxial growth substrate has been removed, wherein the semiconductor structure has a first surface, a side surface and a second surface, wherein the first surface, relative to the second surface, is proximate to the support structure, wherein the second surface is opposite to the first surface, wherein the support structure is thicker than the p-type semiconductor layer, and wherein the support structure is thicker than the n-type semiconductor layer; a p-type electrode disposed on the support structure between the support structure and the p-type semiconductor layer; and an n-type electrode disposed on the second surface of the semiconductor structure, wherein: - the p-type semiconductor layer is a p-type GaN-based layer, the active layer is a GaN-based active layer, the n-type semiconductor layer is a n-type GaN-based layer, such that the semiconductor structure is a GaN-based semiconductor structure, and - the support structure is a metal support structure, the coating layer is a metal coating layer, and the support structure further comprises a metal layer, characterized in that the light-emitting device further comprises a passivation layer disposed on the side surface and the second surface of the GaN-based semiconductor structure, wherein the passivation layer is in contact with the metal support structure, the passivation layer formed as a single piece comprising: a first portion disposed on the second surface of the GaN-based semiconductor structure; and a second portion disposed between the metal support structure and the first surface of the GaN-based semiconductor structure, the first portion being overlapped with the second portion in a thickness direction of the GaN-based semiconductor structure, and the first portion having a width greater than a width of the second portion. a support structure comprising a coating layer; a semiconductor structure disposed on the support structure, the semiconductor structure including a p-type semiconductor layer, an active layer and an n-type semiconductor layer from which an epitaxial growth substrate has been removed, wherein the semiconductor structure has a first surface, a side surface and a second surface, wherein the first surface, relative to the second surface, is proximate to the support structure, wherein the second surface is opposite to the first surface, wherein the support structure is thicker than the p-type semiconductor layer, and wherein the support structure is thicker than the n-type semiconductor layer; a p-type electrode disposed on the support structure between the support structure and the p-type semiconductor layer; and an n-type electrode disposed on the second surface of the semiconductor structure, wherein: - the p-type semiconductor layer is a p-type GaN-based layer, the active layer is a GaN-based active layer, the n-type semiconductor layer is a n-type GaN-based layer, such that the semiconductor structure is a GaN-based semiconductor structure, and - the support structure is a metal support structure, the coating layer is a metal coating layer, and the support structure further comprises a metal layer, - the p-type semiconductor layer is a p-type GaN-based layer, the active layer is a GaN-based active layer, the n-type semiconductor layer is a n-type GaN-based layer, such that the semiconductor structure is a GaN-based semiconductor structure, and - the support structure is a metal support structure, the coating layer is a metal coating layer, and the support structure further comprises a metal layer, characterized in that the light-emitting device further comprises a passivation layer disposed on the side surface and the second surface of the GaN-based semiconductor structure, wherein the passivation layer is in contact with the metal support structure, the passivation layer formed as a single piece comprising: a first portion disposed on the second surface of the GaN-based semiconductor structure; and a second portion disposed between the metal support structure and the first surface of the GaN-based semiconductor structure, a first portion disposed on the second surface of the GaN-based semiconductor structure; and a second portion disposed between the metal support structure and the first surface of the GaN-based semiconductor structure, the first portion being overlapped with the second portion in a thickness direction of the GaN-based semiconductor structure, and the first portion having a width greater than a width of the second portion.