Provided are a light emitting device, a light emitting device package, and a lighting system including the light emitting device and the light emitting device package. The light emitting device includes a light emitting structure, a dielectric, a second electrode layer, a semiconductor region, and a first electrode. The light emitting device includes a plurality of semiconductor layers that form a heterojunction that produces light and a homojunction that protects the device from a reverse current.