Fujitsu Corporation

Junji Komeno

Hitoshi Tanaka

Kazumi Kasai

Hiromi Itoh

Shuzo Kagawa

Tatsuya Oh-hori

A semiconductor photodetector, such as a PIN photodiode and an avalanche photodiode, comprising an InP substrate, a first InP layer, a GaInAs or GaInAsP light absorbing layer, and a second InP layer. All of the layers are successively grown by a vapor phase epitaxial process wherein the lattice constant of the GaInAs (GaInAsP) layer is larger than that of the InP layer at room temperature. The photodetector has a low dark current.

Making a semiconductor photodetector

A transfer chamber is provided between MOCVD reaction chamber and load lock chamber, connected to each chamber through an opening for each, for preventing the reaction chamber from the invasion of foreign gases, which may oxydize metals of MOCVD. The load lock chamber can be evacuated or filled with an inert gas, and has a door to the outside for bringing semiconductor wafers in or out. The transfer chamber is provided with a gas inlet and a gas outlet, through each of them an inert gas is always fed and drained for circulation, and also provided with a transfer mechanism therein for transferring wafers between the load lock chamber and the reaction chamber. Wafers are placed on a susceptor connected to the lid, which is driven by the transfer mechanism. A liner tube for protecting the inner surface of the reaction chamber from undesirable contamination caused by MOCVD reaction may be provided detachably attached to the lid to enclose the wafer. Each opening may be provided with shutter means for sealing each opening while the opening is not sealed by the lid. Oxygen or water vapor undesirably introduced are washed away by the flow of inert gas in the transfer chamber on the way to the reaction chamber.

Apparatus of metal organic chemical vapor deposition for growing

In the vapor phase epitaxy (VPE) method employed for growth of a compound semiconductor, a high resistivity GaAs buffer layer and a low resistivity GaAs active layer are successively grown on a GaAs substrate in a VPE reaction tube. A GaAs substrate having a crystallographic orientation different from that of the GaAs substrate is positioned just above and opposite to the GaAs substrate, thereby decreasing the epitaxial growth rate and impurities in the epitaxial buffer layer grown on the GaAs substrate. To grow the low resistivity active layer, the dummy substrate is moved away from the GaAs substrate downstream from the gas flow direction. This method provides for a low impurity concentration in the buffer layer and a steep doping distribution between the grown epitaxial layers. Advantageously, the yield of the VPE method is enhanced and the noise figure of FETs produced by this VPE method is decreased.

Growing community of inventors

Fujisawa, Japan

Junji Komeno