A semiconductor structure (100) comprising: a substrate (102), a first layer (106) of Al.sub.XGa.sub.YIn.sub.(1−X−Y)N disposed on the substrate, stacks (107, 109) of several second and third layers (108, 110) alternating against each other, between the substrate and the first layer, a fourth layer (112) of Al.sub.XGa.sub.YIn.sub.(1−X−Y)N, between the stacks, a relaxation layer of AlN disposed between the fourth layer and one of the stacks, and, in each of the stacks: the level of Ga of the second layers increases from one layer to the next in a direction from the substrate to the first layer, the level of Ga of the third layers is constant or decreasing from one layer to the next in said direction, the average mesh parameter of each group of adjacent second and third layers increasing from one group to the next in said direction, the thickness of the second and third layers is less than 5 nm.

A light-emitting diode includes a material structure of barrier in the light-emitting well region to improve restriction capacity of electron holes, improving light-emitting efficiency of the LED chip under high temperature. The LED structure includes a Type I semiconductor layer, a Type II semiconductor layer and an active layer between the both, wherein, the active layer is a multi-quantum well structure alternatively composed of well layers and barrier layers, in which, the first barrier layer is a first AlGaN gradient layer in which aluminum components gradually increase in the direction from the Type I semiconductor layer to the quantum well, and the barrier layer at the middle of well layers is an AlGaN/GaN/AlGaN multi-layer barrier layer, and the last barrier layer is a second AlGaN gradient layer in which aluminum components gradually decrease in the direction from the quantum well to the Type II semiconductor layer.

A light-emitting diode includes a material structure of barrier in the light-emitting well region to improve restriction capacity of electron holes, improving light-emitting efficiency of the LED chip under high temperature. The LED structure includes a Type I semiconductor layer, a Type II semiconductor layer and an active layer between the both, wherein, the active layer is a multi-quantum well structure alternatively composed of well layers and barrier layers, in which, the first barrier layer is a first AlGaN gradient layer in which aluminum components gradually increase in the direction from the Type I semiconductor layer to the quantum well, and the barrier layer at the middle of well layers is an AlGaN/GaN/AlGaN multi-layer barrier layer, and the last barrier layer is a second AlGaN gradient layer in which aluminum components gradually decrease in the direction from the quantum well to the Type II semiconductor layer.

A selection transistor and a light-emitting transistor are formed in a pixel. The selection transistor includes a gate electrode connected to a scan line, a first source/drain electrode connected to a signal line, and a second source/drain electrode. The light-emitting transistor includes a gate electrode connected to the second source/drain electrode of the selection transistor, a first electrode connected to a first line, a second electrode connected to a second line, and a channel layer including quantum dots. The light-emitting transistor controls the quantum dots to emit light by a carrier flowing through the channel layer.

Embodiments relate to a light emitting device, a light emitting device package, and a lighting system comprising the same. The light emitting device according to embodiments may comprise: a first conductivity-type semiconductor layer; an active layer on the first conductivity-type semiconductor layer; an electron blocking layer on the active layer; and a second conductivity-type semiconductor layer on the electron blocking layer. The electron blocking layer may comprise an In.sub.xAl.sub.yGa.sub.1-x-yN based superlattice layer (wherein 0≦x≦1, 0≦y≦1).

Embodiments relate to a light emitting device, a light emitting device package, and a lighting system comprising the same. The light emitting device according to embodiments may comprise: a first conductivity-type semiconductor layer; an active layer on the first conductivity-type semiconductor layer; an electron blocking layer on the active layer; and a second conductivity-type semiconductor layer on the electron blocking layer. The electron blocking layer may comprise an In.sub.xAl.sub.yGa.sub.1-x-yN based superlattice layer (wherein 0≦x≦1, 0≦y≦1).

A semiconductor light source that includes a substrate B and a plurality of semiconductor light-emitting rods extending respectively from the substrate, and a plurality of separating walls also extending from the substrate. The separating walls are arranged between the rods in such a way as to define groups of rods, and such that at least two separating walls have a different height.

A semiconductor light source that includes a substrate B and a plurality of semiconductor light-emitting rods extending respectively from the substrate, and a plurality of separating walls also extending from the substrate. The separating walls are arranged between the rods in such a way as to define groups of rods, and such that at least two separating walls have a different height.

A light-emitting diode (LED) package includes a light-emitting structure, an optical wavelength conversion layer on the light-emitting structure, and an optical filter layer on the optical wavelength conversion layer. The light-emitting structure includes a first-conductivity-type semiconductor layer, an active layer on the first-conductivity-type semiconductor layer, and a second-conductivity-type semiconductor layer on the active layer, and emits first light having a first peak wavelength. The optical wavelength conversion layer absorbs the first light emitted from the light-emitting structure and emits second light having a second peak wavelength different from the first peak wavelength. The optical filter layer reflects the first light emitted from the light-emitting structure and transmits the second light emitted from the optical wavelength conversion layer.

A light-emitting diode (LED) package includes a light-emitting structure, an optical wavelength conversion layer on the light-emitting structure, and an optical filter layer on the optical wavelength conversion layer. The light-emitting structure includes a first-conductivity-type semiconductor layer, an active layer on the first-conductivity-type semiconductor layer, and a second-conductivity-type semiconductor layer on the active layer, and emits first light having a first peak wavelength. The optical wavelength conversion layer absorbs the first light emitted from the light-emitting structure and emits second light having a second peak wavelength different from the first peak wavelength. The optical filter layer reflects the first light emitted from the light-emitting structure and transmits the second light emitted from the optical wavelength conversion layer.