1. A light-emitting device, comprising: an epitaxial structure comprising a lower cladding layer of first conductivity type, an active layer comprising InGaN or AlGaInN on the lower cladding layer, and an upper cladding layer of second conductivity type on the active layer; a tunneling structure on the epitaxial structure comprising a first tunneling layer of second conductivity type with a doping concentration greater than 6×10 19 /cm 3 on the upper cladding layer, and a second tunneling layer of first conductivity type with a doping concentration greater than 6×10 19 /cm 3 on the first tunneling layer; and a current spreading layer of first conductivity type comprising AlInN on the tunneling structure.