Sumitomo Chemical Company, Limited

Hitachi Cable, Inc.

Ryota Isono

Takeshi Tanaka

Takashi Takeuchi

There is provided a Group III nitride stack in which the concentration of an impurity in the buffer/channel layer of an HEMT is suppressed to a predetermined range. The Group III nitride stack includes a first layer comprising gallium nitride, and a second layer on the first layer, the second layer comprising a Group III nitride having a lower electron affinity than gallium nitride. The first layer includes a lower layer and an upper layer on the lower layer. The carbon concentration in the upper layer is lower than a carbon concentration in the lower layer, the hydrogen concentration in the upper layer is lower than a hydrogen concentration in the lower layer, the carbon concentration in the upper layer is 5×10cmor less, and the hydrogen concentration in the upper layer is 1×10cmor less.

Group III nitride stack

There is provided a group III nitride laminate, including: a substrate comprised of silicon carbide; a first layer comprised of aluminum nitride and formed on the substrate; a second layer comprised of gallium nitride and formed on the first layer; and a third layer formed on the second layer and comprised of group III nitride having an electron affinity lower than that of the gallium nitride which is comprised in the second layer, the second layer having a thickness of less than 500 nm, the second layer containing iron at a concentration of less than 1&#xd7;10/cm, and the second layer containing carbon at a concentration of less than 1&#xd7;10/cm.

Group-III nitride laminate

A field effect transistor (FET) with high withstand voltage and high performance is realized by designing a buffer layer structure appropriately to reduce a leakage current to 1&#xd7;10A or less when a low voltage is applied. An epitaxial wafer for a field effect transistor comprising a buffer layer, an active layer, and a contact layer on a semi-insulating substratefrom the bottom, and the buffer layerincludes a plurality of layers, and a p-type buffer layer composed of p-type AlGaAs (0.3&#x2266;x&#x2266;1) is provided as a bottom layer (undermost layer). A Nd product of a film thickness of the p-type buffer layer and a p-type carrier concentration of the p-type buffer layer is within a range from 1&#xd7;10to 1&#xd7;10/cm.

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Hitachi, Japan

Ryota Isono