Semiconductor light emitting device

A light emitting device comprising:

• a substrate layer;
• a first layer which comprises at least one layer and which is disposed above the substrate layer;
• an active layer which has a multiple quantum well structure and which is disposed above the first layer;
• and
• a second layer which is disposed above the active layer, and which comprises a semiconductor cladding layer, a current-diffusion layer, and an intermediate layer located above the current-diffusion layer, the second layer having a two-dimensional periodic structure in a surface thereof, wherein the two-dimensional periodic structure is formed above the current-diffusion layer,
• wherein the first layer includes at least one layer having a refractive index that is lower than a thickness-weighted-average of refractive indices of the active layer and lower than a refractive index of a layer of the second layer that is adjacent to the active layer,
• wherein each constituent layer of the second layer other than the intermediate layer has a lower refractive index than the thickness-weighted-average of the refractive indices of the active layer, and
• wherein the intermediate layer has a refractive index that is less than or equal to the thickness-weighted-average of refractive indices of the active layer and that is higher than a refractive index of the semiconductor cladding layer.

A light emitting device comprising:

• a substrate layer;
• a first layer which comprises at least one layer and which is disposed above the substrate layer;
• an active layer which has a multiple quantum well structure and which is disposed above the first layer;
• and
• a second layer which is disposed above the active layer, and which comprises a semiconductor cladding layer, a current-diffusion layer, and an intermediate layer located above the current-diffusion layer, the second layer having a two dimensional periodic structure in a surface thereof, wherein the two-dimensional periodic structure is formed above the current diffusion layer,
• wherein the first layer includes at least one layer having a refractive index that is lower than a thickness-weighted-average of refractive indices of the active layer and lower than a refractive index of a layer of the second layer that is adjacent to the active layer,
• wherein each constituent layer of the second layer other than the intermediate layer has a lower refractive index than the thickness-weighted-average of the refractive indices of the active layer, and
• wherein the intermediate layer has a refractive index that is less than or equal to a refractive index of a well layer of the multiple quantum well structure and that is higher than a refractive index of the semiconductor cladding layer.

A light emitting device comprising:

• a substrate layer;
• a first layer which is disposed above the substrate layer, and which comprises at least one layer including a semiconductor cladding layer of a first conductivity type;
• an active layer disposed above the first layer;
• and
• a second layer which is disposed above the active layer, and which has a two-dimensional periodic structure in a surface thereof, the second layer comprising multiple layers including a semiconductor cladding layer of a second conductivity type and an intermediate layer having a refractive index that is less than or equal to a refractive index of the active layer and that is higher than a refractive index of any other constituent layer of the second layer, wherein the intermediate layer is provided outside the two-dimensional periodic structure.

A light emitting device comprising:

• a substrate layer;
• a first layer which comprises at least one layer and which is disposed above the substrate layer;
• an active layer which has a multiple quantum well structure and which is disposed above the first layer;
• and
• a second layer which is disposed above the active layer, and which has a two-dimensional periodic structure in a surface thereof, the second layer comprising multiple layers including an intermediate layer having a refractive index that is less than or equal to a refractive index of a well layer of the multiple quantum well structure and that is higher than a refractive index of any other constituent layer of the second layer, wherein the intermediate layer is provided outside the two-dimensional periodic structure.