Abstract: According to the present invention, a composite semiconductor substrate (1) for epitaxial growth of a compound semiconductor material (1) comprises a ceramic semiconductor support layer (4), and a single crystalline epitaxial layer (3) formed of the compound semi-conductor material on the ceramic semiconductor support layer.

Abstract: An LED chip (1) grown on an electrically insulating substrate (4) comprises a lower current-distributing layer (5) of a first conductivity type, a first electrode (2), a vertical layer structure (5, 6, 7), the last two being formed on the lower current-distributing layer horizontally separated from each other, the vertical layer structure comprising an active layer (6) and an upper current-distributing layer (8) of a second conductivity type above the active layer, and a second electrode (3) formed on the upper current-distributing layer, the geometry of the electrodes being adjusted to provide a horizontal distance between the electrodes lower than the current spreading length of the chip. According to the present invention, a vertical trench (9) is formed between the electrodes (2, 3), the trench extending through the chip (1), including the lower current-distributing layer (5), for controlling the horizontal current flow in order to achieve a uniform current density over the active layer (6).

Abstract: A semiconductor structure is formed of nitrides of group III metals having wurtzite crystal structure and grown in vapor phase on a (0001) oriented semiconductor substrate. The structure comprises a bottom cladding layer, a top cladding layer, and a diffusion region positioned between the cladding layers for diffusing light propagating within the semiconductor structure. The diffuse region has refractive index different from those of the cladding layers and non-flat surfaces for providing light diffusing interfaces between the diffusion region and the cladding layers. According to the invention, the diffusion region comprises a plurality of diffusion layers, compositions and thicknesses of said diffusion layers having been chosen to avoid formation of strain-induced dislocations in the diffusion region, and adjacent diffusion layers having different refractive indices in order to further enhance the diffusion efficiency.

Abstract: A strained semiconductor heterostructure (10) comprises an injection region comprising a first emitter layer (11) having p-type conductivity and a second emitter layer (12) having n-type conductivity, and a light generation layer (13) positioned between the first emitter layer (11) and the second emitter layer (12). An electron capture region (14) is positioned between the light generation layer (13) and the second emitter layer (12), said electron capture region comprising a capture layer (16) adjacent to the second emitter layer, and a confining layer (15) adjacent to said electron capture layer. According to the present invention, the widths and materials of the confining and capture layers (15, 16) are selected to provide energy difference between one of localized energy levels for electrons in the capture layer (16) and the conduction band bottom of the second emitter layer (12) equal to the energy of the optical phonon.

Abstract: A semiconductor structure is formed of nitrides of group III metals having wurtzite crystal structure and grown in vapor phase on a (0001) oriented semiconductor substrate. The structure comprises a bottom cladding layer, a top cladding layer, and a diffusion region positioned between the cladding layers for diffusing light propagating within the semiconductor structure. The diffuse region has refractive index different from those of the cladding layers and non-flat surfaces for providing light diffusing interfaces between the diffusion region and the cladding layers. According to the invention, the diffusion region comprises a plurality of diffusion layers, compositions and thicknesses of said diffusion layers having been chosen to avoid formation of strain-induced dislocations in the diffusion region, and adjacent diffusion layers having different refractive indices in order to further enhance the diffusion efficiency.

Abstract: An LED chip (1) grown on an electrically insulating substrate (4) comprises a lower current-distributing layer (5) of a first conductivity type, a first electrode (2), a vertical layer structure (5, 6, 7), the last two being formed on the lower current-distributing layer horizontally separated from each other, the vertical layer structure comprising an active layer (6) and an upper current-distributing layer (8) of a second conductivity type above the active layer, and a second electrode (3) formed on the upper current-distributing layer, the geometry of the electrodes being adjusted to provide a horizontal distance between the electrodes lower than the current spreading length of the chip. According to the present invention, a vertical trench (9) is formed between the electrodes (2, 3), the trench extending through the chip (1), including the lower current-distributing layer (5), for controlling the horizontal current flow in order to achieve a uniform current density over the active layer (6).