Sharp Kabushiki Kaisha Corporation

Stephen Peter Najda

Robert George Brown

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. In an alternative embodiment, the cladding regions have a graded composition, with their composition at the interface with the optical confinement layers being such that the DX level in the cladding regions is degenerate with the X-conduction band in the optical confinement layers.

Semiconductor laser device

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.

Optical semiconductor device

Semiconductor device

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 In Ga P 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.

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.

Optoelectronic semiconductor device

A color semiconductor display device in which optoelectronic elements capable of emitting/absorbing light of different predetermined wavelengths in the visible wavelength range (e.g. red, green, blue) are formed on a common substrate and comprise similar alloy compositions which are lattice matched to the substrate material. The alloy is preferably a III-V nitride alloy lattice matched to Si or GaP substrate material. In the disclosed embodiment, a color display device comprises a silicon or GaP substrate with an array of pixels, each being formed by a group of three (red, green, blue) color sub-pixels provided on the substrate. The pixels are formed of InAINSb alloy, with a quantum well regions of InNSb and barrier regions of AINSb, or are formed of AIGaAsSbN alloy, with quantum well regions of GaAsN and barrier regions of AINSb. Tuning of the wavelength emission/absorption characteristics of the sub-pixels is by doping of the quantum well material with aluminum and/or by quantum confinement.

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Oxford, United Kingdom

Stephen Peter Najda