Kabushiki Kaisha Toshiba

Masahisa Funemizu

Yuzo Hirayama

Masaki Tohyama

Yasuo Ohba

Kazuhiro Inoue

Mitsuhiro Kushibe

Kazuhiro Eguchi

Takao Noda

Keiji Takaoka

Yoshihiro Kokubun

Motoyasu Morinaga

Yasuo Ashizawa

Makoto Ohashi

In order to realize an optical semiconductor device having a window structure promising high-speed operation and highly efficient coupling with optical fibers and to realize its manufacturing method, the device has a window structure in which an optical guide layer is partly removed near the emission facet to decrease the facet reflectivity. Since a cladding layer has a narrow mesa structure also in a window region, the parasitic capacitance can be reduced, and high-speed modulation is ensured. Although light runs through the window region in spread directions from one end of the optical guide layer toward the emission facet, the cladding layer changes its width or thickness in accordance with the spread angle of light. Therefore, light is not reflected or scattered by side surfaces of the cladding layer, and prevents a decrease in optical output due to a scattering loss, or a deterioration in distribution of emitted light. As a result, the device has a high coupling efficiency with optical fibers, and is operative for high optical output.

Optical semiconductor device and its manufacturing method

A grating coupled surface emitting laser has a diffraction grating of a second or higher order for guided-mode light part of a waveguide region, and extract a beam in a direction perpendicular to the waveguide region. By narrowing a stripe of the waveguide region around the center, the phase of the diffraction grating is shifted to attain a Gaussian distribution for radiation-mode light in a cross section along the waveguiding direction.

Grating coupled surface emitting device

A p-type GaAs or AlGaAs thin film is formed by a MOCVD method. In the growing step of the thin film, the thin film is doped with a high concentration of carbon atoms forming an acceptor level such that the carrier concentration of the thin film falls within the range of between 1.times.10.sup.18 cm.sup.-3 and 1.times.10.sup.20 cm.sup.-3. At least one of trimethyl gallium and trimethyl aluminum is used as a raw material gaseous compound of III-group element, and arsine is used as a raw material gaseous compound of V-group element. The thin film is formed by an epitaxial growth under the molar ratio V/III of the V-group element supply rate to the III-group element supply rate, which is set at such a small value as 0.3 to 2.5, the temperature of 450 to 700.degree. and the pressure of 1 to 400 Torr. The thin film formed under these conditions exhibits a mirror-like smooth surface, and the film-growth rate is dependent on the supply rate of the V-group element.

Method of manufacturing a p-type compound semiconductor thin film

Growing community of inventors

Yokohama, Japan

Masahisa Funemizu