Ntt Electronics Corporation

Nippon Telegraph and Telephone Corporation

Tadao Ishibashi

Kenji Kobayashi

Seigo Ando

Yoshifumi Muramoto

Ken Tsuzuki

Haruki Yokoyama

Makoto Shimizu

Hiroki Itoh

Yukihiro Hirota

Nobuhiro Kikuchi

Masahiro Nada

Yutaka Matsuoka

Isamu Kotaka

Hiroshi Tomita

Fumito Nakajima

Kazuhiro Maruyama

Toshihide Yoshimatsu

Mitsuteru Ishikawa

Eiichi Sano

Kenji Kurishima

Hiroki Nakajima

Yoshiki Yamauchi

Naofumi Shimizu

Tomofumi Furuta

Koichi Nagata

Masaaki Tomizawa

Atsushi Wakatsuki

Tomoyuki Akeyoshi

A semiconductor element capable of adjusting a barrier height &#x3d5;and performing zero-bias operation and impedance matching with an antenna for improving detection sensitivity of high-frequency RF electric signals, a method of manufacturing the same, and a semiconductor device having the same. In the semiconductor element, a concentration of InGaAs (n-type InGaAs layer) is intentionally set to be high over a range for preventing the 'change of the barrier height caused by the bias' described above up to a deep degeneration range. An electron Fermi level (E) increases from a band edge of InGaAs (n-type InGaAs layer) to a band edge of InP (InP depletion layer).

Semiconductor element, semiconductor device, and method for manufacturing same

An opto-electronic integrated circuit includes an optical splitter (A,B) formed on a substrate, the optical splitter branching an input optical signal into N (N is an integer of 2 or more) optical signals, and outputting the optical signals, and N optical phase modulators (A-D) formed on the substrate for the respective optical signals output from the optical splitter, the optical phase modulators adjusting the phases of the optical signals based on a phase modulation characteristic in which the phase change amount changes depending on the wavelength of light, and output the optical signals.

Opto-electronic integrated circuit, array antenna transmitter, array antenna receiver, and transmitter

A photodiode that can provide a THz operation with a stable output. A photodiode having a pin-type semiconductor structure includes a semiconductor layer structure and n and p electrodes. The semiconductor layer structure is obtained by sequentially layering an n-type contact layer, a low concentration layer, and a p-type contact layer. The low concentration layer is obtained by layering an electron drift layer, a light absorption layer, and a hole drift layer while being abutted to the n-type contact layer. The n electrode and the p electrode are connected to the n-type contact layer and the p-type contact layer, respectively. During operation, the low concentration layer is depleted.

Photodiode

An integrated optoelectronic module comprising: a semiconductor substrate; a single-mode optical waveguide comprising a semiconductor with a signal input section at a first end; a multi-mode optical waveguide comprising a semiconductor connected to a second end of the single-mode optical waveguide; and a photodiode disposed on and adjacent to the multi-mode interferometer waveguide and having at least one optical absorption layer section, wherein the single-mode optical waveguide, the multi-mode optical waveguide, and the photodiode being stacked on the semiconductor substrate, wherein the multi-mode interferometer waveguide comprises a reflection section formed by partly grooving the multi-mode interferometer waveguide, and an optical signal having propagated through the multi-mode interferometer waveguide is reflected by the reflection section and focused on the optical absorption layer section.

Integrated optoelectronic module

An APD is provided with the semi-insulating substrate, a first mesa having a first laminate constitution in which a p-type electrode layer, a p-type light absorbing layer, a light absorbing layer with a low impurity concentration, a band gap inclined layer, a p-type electric field control layer, an avalanche multiplier layer, an n-type electric field control layer, and an electron transit layer with a low impurity concentration are stacked in this order on a surface of the semi-insulating substrate, a second mesa having an outer circumference provided inside an outer circumference of the first mesa as viewed from the laminating direction and having a second laminate constitution in which an n-type electrode buffer layer and an n-type electrode layer are stacked in this order on a surface on the electron transit layer side, and a depletion control region that is provided in layers on the second mesa side relative to the p-type electric field control layer, formed in an encircling portion provided inside an outer circumference of the first mesa and encircling an outer circumference of the second mesa, and prevents the encircling portion of the p-type electric field control layer from being depleted when bias is applied.

Avalanche photodiode

A layer in which the potential level difference normally unrequired for device operation is generated is positively inserted in a device structure. The potential level difference has such a function that even if a semiconductor having a small bandgap is exposed on a mesa side surface, a potential drop amount of the portion is suppressed, and a leakage current inconvenient for device operation can be reduced. This effect can be commonly obtained for a heterostructure bipolar transistor, a photodiode, an electroabsorption modulator, and so on. In the photodiode, since the leakage current is alleviated, the device size can be reduced, so that in addition to improvement of operating speed with a reduction in series resistance, it is advantageous that the device can be densely disposed in an array.

Semiconductor device

An APD is provided with a semi-insulating substrate, a first mesa having a first laminate constitution in which a p-type electrode layer, a p-type light absorbing layer, a light absorbing layer with a low impurity concentration, a band gap inclined layer, a p-type electric field control layer, an avalanche multiplier layer, an n-type electric field control layer, and an electron transit layer with a low impurity concentration are stacked in this order on a surface of the semi-insulating substrate, a second mesa having an outer circumference provided inside an outer circumference of the first mesa as viewed from the laminating direction and having a second laminate constitution in which an n-type electrode buffer layer and an n-type electrode layer are stacked in this order on a surface on the electron transit layer side of the first mesa, and in the APD, a total donor concentration of the n-type electric field control layer is lower than a total acceptor concentration of the p-type electric field control layer in a range of 2&#xd7;10to 1&#xd7;10/cm.

An electron injected APD with an embedded n electrode structure in which edge breakdown can be suppressed without controlling the doping profile of an n-type region of the embedded n electrode structure with high precision. The APD comprising a buffer layer with a low ionization rate is inserted between an n electrode connecting layer and an avalanche multiplication layer. Specifically, the APD is an electron injected APD in which an n electrode layer, the n electrode connecting layer, the buffer layer, the avalanche multiplication layer, an electric field control layer, a band gap gradient layer, a low-concentration light absorbing layer, a p-type light absorbing layer, and a p electrode layer are sequentially stacked, and a light absorbing portion that includes at least the low-concentration light absorbing layer and the p-type light absorbing layer forms a mesa shape.

A semiconductor optical modulator that includes a first semiconductor optical waveguide having a laminated structure including a core layer, a first clad layer, a second clad layer, and a barrier layer, the first clad layer and the second clad layer being disposed below and above the core layer, the barrier layer being inserted between the second clad layer and the core layer; a second semiconductor optical waveguide having a laminated structure in which the second clad layer has a p-type semiconductor penetrating locally through a n-type semiconductor in a laminated direction in the laminated structure of the first semiconductor optical waveguide; a first electrode connected to the first clad layer of the first semiconductor optical waveguide; and a second electrode electrically connecting the second clad layer of the first semiconductor optical waveguide and the p-type semiconductor of the second clad layer of the second semiconductor optical waveguide.

Semiconductor optical modulator and optical modulating apparatus

The present invention can provide an npin-type optical modulator that has a high withstand voltage and is easily fabricated. A semiconductor optical amplifier () according to an embodiment of the present invention is an npin-type semiconductor optical modulator in which layers are sequentially stacked, with a cathode layer (-) arranged on the substrate side, including at least a first n-type cladding layer (-), a p-type cladding layer (), a core layer () and a second n-type cladding layer (-). In this semiconductor optical modulator, the p-type cladding layer () is electrically connected to an electrode (-) of the cathode layer. Accordingly, the accumulation of holes in the p-type cladding layer associated with light absorption in the npin-type optical modulator can be absorbed in the electrode on the negative side. This npin-type semiconductor optical modulator can be comparatively easily fabricated using conventional semiconductor manufacturing techniques by adopting a mesa type waveguide structure.

Semiconductor optical modulator

In an electron-injection type APD, it is necessary to prevent a dark current increase and to secure the life time of the device. It is demanded to improve reliability of the APD with a lower production cost. With the InP buffer layer having an n-type doping region on the inside of a region defined by an optical absorption layer, a predetermined doping profile is achieved by ion implantation. Thus, electric field concentration in the avalanche multiplication layer is relaxed. Furthermore, a low-concentration second optical absorption layer is provided between the optical absorption layer and the avalanche multiplication layer. Responsivity of the optical absorption layer is maximized, and depletion of the lateral surface of the optical absorption layer is prevented; thus, electric field concentration is prevented. Preventing edge breakdown, the device improves its reliability.

Avalanche photodiode having doping region with monotonically increasing concentration distribution

The present invention relates to a semiconductor optoelectronic waveguide having a nin-type hetero structure which is able to stably operate an optical modulator. On the upper and lower surfaces of the core layer determined for the structure so that electro-optical effects are effectively exerted at an operating light wavelength and are provided with intermediate clad layers having a band gap which is greater than that of the core layer. Respectively on the upper and the lower surface of the intermediate clad layer are provided the clad layers having the band gap which is greater than those of the intermediate clad layers. On the upper surface of the clad layer are sequentially laminated a p-type layer and an n-type layer. In the applied voltage range used under an operating state, a whole region of the p-type layer and a part or a whole region of the n-type layer are depleted.

Semiconductor optoelectronic waveguide

An ultra high speed APD capable of realizing reduction in an operating voltage and quantum efficiency enhancement at the same time is provided. Under operating conditions APD, a doping concentration distribution of each light absorbing layer is determined so that a p-type light absorbing layer () maintains a p-type neutrality except a part thereof, and a low concentration light absorbing layer () is depleted. Moreover, a ratio between a layer thickness Wof the p-type light absorbing layer () and a layer thickness Wof the low concentration light absorbing layer () is determined so that W&#x3e;0.3 &#x3bc;m and a delay time of an element response accompanying a transit of carriers generated in the light absorbing layer by light absorption takes on a local minimum under a condition that a layer thickness W(=W+W) of the light absorbing layer is constant.

Growing community of inventors

Yokohama, Japan

Tadao Ishibashi