Abstract: Quantum cascade lasers (QCLs), and methods of manufacture of QCLs, comprising an active portion. In some embodiments, the active portion can comprise: a plurality of tensiley strained quantum barrier layers, each comprising GayIn1-yAs; and a plurality of compressively strained quantum well layers, each comprising GaxIn1-xAs. In some embodiments, the active portion can comprise: a plurality of compressively strained quantum barrier layers, each comprising AlyIn1-yAs; and a plurality of tensiley strained quantum well layers, each comprising GaxIn1-xAs. The active portion can be grown on InP substrate.

Abstract: An embodiment of the invention relates to a cascade semiconductor light source comprising: a first block of cascades and a first contact region coupled to said first cascade, the first contact region being capable of injecting carriers into the first cascade of the first block; and a second block of cascades and a second contact region coupled to said second cascade, the second contact region being capable of injecting carriers into the second cascade; wherein the application of a first polarity voltage to said light source results in the cascades in the first block to be in an active mode and the cascades in the second block to be in an inactive mode; wherein the application of a second, opposite polarity voltage to said light source results in the cascades in the first block to be in an inactive mode and the cascades in the second block to be in an active mode; wherein the first block of cascades is adapted to emit light at a first wavelength in its active mode and to passively conduct electrical current in

Abstract: A semiconductor device according to the invention for emitting light when a voltage is applied includes a first (3), a second (5) and a third active semiconductor region (7A-7C). While the conductivity of the first semiconductor region (3) is based on charge carriers of a first conductivity type, the conductivity of the second semiconductor region (5) is based on charge carriers of a second conductivity type, which have a charge opposite to the charge carriers of the first conductivity type The active semiconductor region (5 13) is arranged between the first and the second semiconductor regions (3, 5). Embedded in the active semiconductor region (5) are quantum structures (13) which are made from a semiconductor material which has a direct band gap. In that respect the term quantum structures is used to denote structures which in at least one direction of extent are of a dimension which is so small that the properties of the structure are substantially also determined by quantum-mechanical processes.

Abstract: An inventive semiconductor device for emitting light when applying a voltage comprises: a first semiconductor region (3) whose conductivity is based on charge carriers of a first type of conductivity, e.g. electrons; a second semiconductor region (5) whose conductivity is based on charge carriers of a second type of conductivity, e.g. holes, which have a charge opposite that of the charge carriers of the first type of conductivity and; an active semiconductor region (7A 7C), which is situated between the first semiconductor region (3) and the second semiconductor region (5) and in which the emission of light occurs, these regions being embedded in the quantum structures (13, 15) of a semiconductor material having a direct band gap in at least two different intercoupled configurations.

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).