Abstract: The invention relates inter alia to a photoconductor (10) comprising a multilayer (13) which comprises a plurality of photoconductive semiconductor layers (131-134). According to the invention, the multilayer (13) comprises at least two sublayers (130) which each comprise at least a first photoconductive semiconductor layer (131) and a second photoconductive semiconductor layer (132), wherein the first and the second photoconductive semiconductor layer (131, 132) are doped to different degrees for each of the sublayers (130).

Abstract: A terahertz antenna includes at least one photoconductive layer which generates charge carriers upon irradiation of light and two electroconductive antenna elements via which an electric field can be applied to at least one section of the photoconductive layer. The photoconductive layer being doped with a dopant in a concentration of at least 1×1018 cm?3, the dopant being a transition metal. The photoconductive layer is produced by molecular beam epitaxy at a growth temperature of at least 200° C. and not more than 500° C., the dopant being arranged in the photoconductive layer such that it produces a plurality of point defects.

Abstract: A terahertz antenna includes at least one photoconductive layer which generates charge carriers upon irradiation of light and two electroconductive antenna elements via which an electric field can be applied to at least one section of the photoconductive layer. The photoconductive layer being doped with a dopant in a concentration of at least 1×1018 cm?3, the dopant being a transition metal. The photoconductive layer is produced by molecular beam epitaxy at a growth temperature of at least 200° C. and not more than 500° C., the dopant being arranged in the photoconductive layer such that it produces a plurality of point defects.

Abstract: A quantum cascade laser structure having a plurality of cascades each of which comprises a number of alternately arranged quantum wells and barriers of different thicknesses and heights, wherein at least one of the quantum wells and at least one of the barriers is under mechanical strain and the quantum wells and the barriers are coordinated such that the existing mechanical strains are largely compensated within one cascade, wherein each of the barriers comprise one or more barrier layers, wherein each cascade comprises a thinnest quantum well, a lowest barrier, a thickest quantum well, a highest barrier, and the highest barrier is followed by alternately arranged quantum wells and barriers.

Abstract: A quantum cascade laser structure having a plurality of cascades each of which comprises a number of alternately arranged quantum wells and barriers of different thicknesses and heights, wherein at least one of the quantum wells and at least one of the barriers is under mechanical strain and the quantum wells and the barriers are coordinated such that the existing mechanical strains are largely compensated within one cascade, wherein each of the barriers comprise one or more barrier layers, wherein each cascade comprises a thinnest quantum well, a lowest barrier, a thickest quantum well, a highest barrier, and the highest barrier is followed by alternately arranged quantum wells and barriers.

Abstract: A quantum well structure according to the invention includes a quantum well layer (107) arranged between two barrier layers (109, 112). It is distinguished in that at least one of the barrier layers (109) includes nanostructures (110) which compensate or modulate a lateral homogeneity of the barrier layer (109), that exists without the nanostructures (110), that is to say a homogeneity in the directions extending perpendicularly to the stacking direction of the layers in the quantum well structure.

Abstract: A quantum cascade laser structure in accordance with the invention comprises a number of cascades (100), each of which comprises a number of alternately arranged quantum wells (110a to 110j) and barrier layers (105 to 105j). The material of at least one quantum well (110a to 110j) as well as the material of at least one barrier layer (105 to 105j) is under mechanical strain, with the respective strain being either a tensile strain or a compression strain. The quantum wells (110a to 110j) and barrier layers (105 to 105j) are engineered in the quantum cascade laser structure in accordance with the invention so that existing strains are largely compensated within a cascade (100). In the quantum cascade laser structure in accordance with the invention, each material of the quantum wells (110a to 110j) has only one constituent material and the material of at least one barrier layer (105d, 105e, 105f) has at least two constituent materials (111a, 111b, 112a, 112b, 113a, 113b).

Abstract: A quantum cascade laser structure in accordance with the invention comprises a number of cascades (100), each of which comprises a number of alternately arranged quantum wells (110a to 110j) and barrier layers (105 to 105j). The material of at least one quantum well (110a to 110j) as well as the material of at least one barrier layer (105 to 105j) is under mechanical strain, with the respective strain being either a tensile strain or a compression strain. The quantum wells (110a to 110j) and barrier layers (105 to 105j) are engineered in the quantum cascade laser structure in accordance with the invention so that existing strains are largely compensated within a cascade (100). In the quantum cascade laser structure in accordance with the invention, each material of the quantum wells (110a to 110j) has only one constituent material and the material of at least one barrier layer (105d, 105e, 105f) has at least two constituent materials (111a, 111b, 112a, 112b, 113a, 113b).