Light emitting device and system providing white light with various color temperatures

A light emitting device comprising:

• a light emitting element which is operated by a forward driving bias to emit first light and includes a first conductive layer of a first conductivity type, a second conductive layer of a second conductivity type, a light emitting layer disposed between the first conductive layer and the second conductive layer, a first electrode connected to the first conductive layer, and a second electrode connected to the second conductive layer, wherein the first conductive layer, the second conductive layer and the light emitting layer are represented by InxAlyGa(1-x-y)N (0≦x≦1, 0≦y≦1);
• and
• a phosphor layer including a phosphor which partially wavelength-converts the first light to emit second light, wherein the phosphor layer includes only the phosphor or a combination of transparent resin and a phosphor,
• wherein the light emitting element emits blue light, the phosphor layer includes a yellow phosphor which partially wavelength-converts the blue light to emit yellow light and a red phosphor which partially wavelength-converts the blue light to emit red light, or a green phosphor which partially wavelength-converts the blue light to emit green light and a red phosphor which partially wavelength-converts the blue light to emit red light, and
• wherein the light emitting device emits white light using the first light and the second light such that a color temperature of the white light is varied by adjusting a level of the driving bias.