Abstract: A semiconductor laser device having a body with opposed facets and including an active region with aluminum diffused into the active region along the facets thereof. Adding aluminum to the portions of the active region along the facets increases the bandgap of the active region along the facets and provides a semiconductor laser device having an increased catastrophic optical damage (COD) level. The semiconductor laser device is produced by depositing a thin film of aluminum on the facets of the semiconductor laser device and then heat treating to cause diffusion of the aluminum film or phosphorus into the body of the semiconductor laser device along the facets thereof, thereby changing the composition of the semiconductor laser device body along the facets. Alternatively, phosphorus may be diffused into the body of the semiconductor laser device along the facets thereof.

Abstract: There is provided a semiconductor laser device capable of emitting a laser beam having stable transverse modes. A ridge type semiconductor laser device comprises an upper clad layer 15 left on its active layer to a thickness (d) between 0.25 and 0.50 m in order to ensure a stable production of fundamental transverse modes for laser operation and a rib-shaped clad layer 16 having a bottom width (W) between 2.0 .mu.m and 3.5 .mu.m and projecting from the upper clad layer in juxtaposition with the light emitting region of the active layer 13. When d and W are found within the respective ranges, the device emits a laser beam having stable transverse modes.

Abstract: In the monolithic integration of HFET and DOES device, a wide band gap carrier confining semiconductor layer is provided only at predetermined locations where DOES devices are desired. This layer is not provided at other predetermined locations where HFET devices are desired as it would constitute a shunt path which would degrade the high frequency operation of the HFET devices. The invention is particularly useful where monolithic integration of optical sources, optical detectors, and electronic amplifying or switching elements is desired.

Abstract: In the monolithic integration of HFET and DOES devices, a wide band gap carrier confining semiconductor layer is provided only at predetermined locations where DOES devices are desired. This layer is not provided at other predetermined locations where HFET devices are desired as it would constitute a shunt path which would degrade the high frequency operation of the HFET devices. The invention is particularly useful where monolithic integration of optical sources, optical detectors, and electronic amplifying or switching elements is desired.

Abstract: An optoelectronic bistable apparatus having a double heterojunction structure comprising a light-emitting first semiconductor layer of n type GaAs interlaid between a second semiconductor layer of n.sup.- type AlGaAs and a third semiconductor layer of p.sup.+ type AlGaAs, the second and third semiconductor layers having a broader energy gap than that of the first semiconductor layer. An extremely thin fourth semiconductor layer of p.sup.+ type GaAs with a high impurity concentration is deposited on the second semiconductor layer. A fifth semiconductor layer of n.sup.- type AlGaAs, n.sup.+ type AlGaAs and n.sup.+ type GaAs is formed on the fourth semiconductor layer. At least a portion of the fifth semiconductor layer which contacts the fourth semiconductor layer has a broader energy gap than that of the second semiconductor layer.