Abstract: An information processor of a high reliability and a high recording density, and a blue color, blue-violet color and violet color based semiconductor light emitting device operable at a low threshold current density, used for the same, are provided. An optical information processor of a high reliability and a high recording density enables a moving picture, such as a high-definition television picture, to be recorded and reproduced satisfactorily. A barrier layer in a quantum-well active layer of a semiconductor light emitting device is doped with n-type impurities at a high density. Alternatively, the face orientation of a quantum-well active layer of a semiconductor light emitting device is a plane inclined from the (0001) plane, whereby the threshold current value of the semiconductor light emitting device can be decreased. The semiconductor light emitting device is typified by a gallium nitride based compound semiconductor laser device.

Abstract: A superlattice APD includes light absorption layer for generating carriers by absorbing light, a multiplication layer for multiplying the carriers, and a pair of electrodes for driving the carriers. The multiplication layer includes a superlattice structure with a well layer less than 10 nm in thickness and a barrier layer more than 10 nm and less than 20 nm in thickness deposited in alternate layers.

Abstract: A semiconductor device includes a region in which carriers are transferred in the lamination direction of a multiple quantum well, such as a multiple quantum well multiplication layer of a superlattice APD. A superlattice structure with a varying well width is introduced to a hetero-interface present in the transfer region, thereby preventing pile-up of the carriers.

Abstract: A semiconductor light-emitting device containing as first and second semiconductor layers a semiconductor of Cd.sub.x Zn.sub.1-x S.sub.y Se.sub.1-y (0<x.ltoreq.1, 0.ltoreq.y.ltoreq.1) and as an active layer a semiconductor of Cd.sub.x Zn.sub.1-x S.sub.y Se.sub.1-y (0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1) formed between the first and second semiconductor layers, if necessary sandwiching the active layer with a pair of light guiding layers, can emit a blue laser light excellent in properties and high in reliability.

Abstract: A wavelength-tunable semiconductor laser device presenting a large wavelength-tunable range or a very-high-speed modulating semiconductor laser device having a distributed feedback structure including a diffraction grating as in the case of a DBR laser or a DFB laser incorporates therein a plurality of active layers differing from one another in constituent elements or composition ratio or thickness for reducing spectral line widths, while improving single-mode spectral oscillation characteristics.

Abstract: Disclosed in a semiconductor laser device for use in a system or apparatus utilizing light for information transmission in optical communication or the like, in which lattice defects or the like are prevented from occurring in the vicinity of a light-emitting active area to thereby reduce a leakage current which substantially makes no contribution to light emission. In order to realize the above semiconductor laser device, a wide gap area for preventing a leakage current is formed to be flat or formed to be spatially apart from the active area.

Abstract: A semiconductor laser having a stripe-like lasing region, wherein the structure of the lasing region such as the mechanism of optical guiding of the lateral mode control structure is made different between the central portion in the lasing region and portions close to facets, in order to reduce optical feedback induced noise and astigmatism, and to facilitate the manufacture thereof.

Abstract: A semiconductor optical device having a region in which semiconductor or carriers in the semiconductor and light are interact, for example, an active region for a semiconductor laser, an optical wave guide region of an optical modulator, etc., includes a quantum well structure having a well region and a barrier region. The semiconductor optical device is remarkably improved with the degree of design freedom as it relates to parameters such as thickness and selection of material without deteriorating the quantum effect, by introducing a super lattice super-layer structure into the barrier region of the quantum well structure or defining the strain for the well region and the barrier region.

Abstract: A wavelength-tunable semiconductor laser device presenting a large wavelength-tunable range or a very-high-speed modulating semiconductor laser device having a distributed feedback structure including a diffraction grating as in the case of a DBR laser or a DFB laser incorporates therein a plurality of active layers differing from one another in constituent elements or composition ratio or thickness for reducing spectral line widths, while improving single-mode spectral oscillation characteristics.

Abstract: A semiconductor laser device of the field modulation type includes a structure in which the threshold carrier density for laser oscillation is reduced so as to enable an effective action of a modulated electric field applied externally on an active region for radiating light, thereby enabling an extremely high speed modulation. A quantum structure which does not fulfill the charge neutrality condition for free-carriers or a strained super lattice structure is adopted as the structure in which the threshold carrier density is reduced.

Abstract: A semiconductor optical device in which an optical waveguide (3, 11) provided on a semiconductor substrate (1) comprises a strained-layer superlattice shows an extremely small transmission loss. A semiconductor optical device with further improved characteristics is obtainable by using a stained-layer superlattice for a portion required to show a great change in refractive index, such as an optical crosspoint switch portion (10), as well as for the optical waveguide (3, 11). The strained-layer superlattice comprises a first semiconductor layer and a second semiconductor layer having a narrower band gap and a greater lattice constant as compared with the first semiconductor layer, the two layers grown periodically.

Abstract: In a well-known semiconductor laser, a multiple quantum well type active layer consisting of barrier layers and active layers or well layers, each of which has a thickness less than the de Broglie wavelength of electrons, is doped with an impurity, and the impurity density is made higher in the barrier layer than in the well layer. Further, in a case where the multiple quantum well active layer is held between p-type and n-type cladding layers, the well layer is undoped, the part of the barrier layer lying in contact with the well layer is undoped, and the other part of the barrier layer close to the p-type cladding layer is put into the n-conductivity type while that of the barrier layer close to the n-type cladding layer is put into the n-conductivity type. Desirably, the impurity density should range from about 1.times.10.sup.18 to about 1.times.10.sup.19 cm.sup.- 3.

Abstract: A semiconductor device comprises a first superlattice layer consisting of a first semiconductor layer that contains impurities and a second semiconductor layer that contains impurities at a low concentration, said first superlattice layer being formed on a semiconductor substrate; and a second superlattice layer that covers that exposed side walls of said first superlattice layer. A disordered region is formed in the vicinity of the first semiconductor layer of the second superlattice layer in order to realize quantum wires with the conventional manufacturing process. This makes it possible to easily fabricate a laser device, a light-emitting diode and a transistor having quantum wires to enhance their performance.

Abstract: A semiconductor laser device is provided with an optical confinement region constituted by first, second, third and fourth semiconductor layers provided on the upper part of a predetermined semiconductor substrate in contact with each other successively. The first and fourth semiconductor layers are smaller in refractive index than the second and third semiconductor layers, and the third semiconductor layer is larger in refractive index than the second semiconductor layer. On the other hand, the second and fourth semiconductor layers are larger in forbidden bandwidth than the third semiconductor layer. At least the first and fourth semiconductor layers are opposite in conductivity type to each other. In addition to this, the optical confinement region is formed into a mesa-stripe, and both side walls of this mesa-stripe which are substantially parallel to the traveling direction of a laser beam are embedded with a fifth semiconductor layer.

Abstract: Disclosed is a semiconductor laser device having at least an optical confinement region which includes a first semiconductor layer, and second and third semiconductor layers holding the first semiconductor layer therebetween and having a greater band gap and a lower refractive index than those of the first semiconductor layer, the second and third semiconductor layers having conductivity types opposite to each other; characterized in that the relationship between a donor density (N.sub.D .times.10.sup.17 cm.sup.-3) of the n-conductivity type semiconductor layer in the second and third semiconductor layers and a proportion (.GAMMA..sub.n %) of an optical output existing in the n-conductivity type semiconductor layer relative to a total optical output of the laser is set at N.sub.D .times..GAMMA..sub.n .gtoreq.500. Noise characteristics are sharply improved.