Abstract: An SCH laser device fabricated in the (Al,Ga,In)P system has an active region disposed within an optical guiding region. The optical guiding region is disposed between an n-doped cladding region and a p-doped cladding region. The laser device is provided with optical confinement layers, which are disposed at the interfaces between the optical guiding region and the cladding regions. The optical confinement regions produce increased confinement of the optical field, and reduce the penetration of the optical field into the cladding regions. The optical confinement region on the p-side of the device also serves as a potential barrier to the transport of electrons into the p-doped cladding region. The cladding regions have a low Al mole fraction, so that they have a direct bandgap. This prevents carrier loss by trapping in the DX level in the cladding regions.

Abstract: An optical semiconductor device comprising: an active region; and a p-doped cladding region disposed on one side of the active region; wherein an electron-reflecting barrier is provided on the p-side of the active region for reflecting both &Ggr;-electrons and X-electrons, the electron-reflecting barrier providing a greater potential barrier to &Ggr;-electrons than the p-doped cladding region.

Abstract: A semiconductor device has a blocking layer disposed between the substrate and the active layer. The blocking layer inhibits the propagation of anti-phase domain defects (APDs) into the active layer. This decreases the density of defects in the active layer, and improves the performance characteristics of the laser device. The blocking layer is disposed either wholly within one of the layers of the laser device, or at the interface between two layers of the laser device. The bandgap of the blocking layer is preferably substantially equal to the bandgap of the layer in which it is disposed, or to the bandgap of a layer to which it is adjacent. This prevents the formation of a potential, barrier, or a potential well in the laser structure, so that provision of the blocking layer does not affect the transport of carriers through the device. In one embodiment the device is a laser device and is fabricated in the (Al,Ga,In)P system.

Abstract: An (Al,Ga,In)P semiconductor laser device has an optical region disposed between n-type and p-type cladding layers. An active region containing quantum well active layers and barrier layers disposed alternately with the quantum well layers is provided within the optical guiding region. Strained layers of InxGal−xP are used as the barrier layers. The active region is thus aluminium-free, and this reduces the oxygen impurity concentration in the active region thereby improving the performance and reliability of the laser. An aluminium-free spacer layer can be provided between one of the cladding layers and the quantum well active layer disposed closest to that cladding layer. The invention may be applied to other semiconductor devices, for example such as an LED.

Abstract: A laser or light emitting diode device has a p-i-n structure and a distributed Bragg reflector having layers alternating with other layers of different refractive indices. These layers are formed of p-type conducting polymer materials which are electrically conducting polymer materials which are electrically conducting and transparent at the emission wavelength of the device.