Abstract: A first semiconductor layer (102) is formed on a substrate (101) by crystal growth of a first nitride semiconductor in a direction along a c-axis. A second semiconductor layer (103) made of a second nitride semiconductor having a band-gap energy larger than that of the first nitride semiconductor is formed on the first semiconductor layer (102). A polarity inversion layer (104) made of AlN and having a Group-V polar surface on a partial region on the second semiconductor layer (103) is formed.

Abstract: An integrated circuit suitable for use in signal frequency bands of 1 THz or higher is provided. The integrated circuit comprises: a substrate at least whose uppermost plane is a single crystal of silicon carbide with a vertical plane intersecting the uppermost plane and extending downwardly therefrom, and a lower plane substantially parallel to the uppermost plane and intersecting the vertical plane; and a single-crystal graphene layer provided in contact with the uppermost plane of the substrate. In the integrated circuit, a short-gate-length transistor and an antenna element are integrally formed.

Abstract: In a first step S101, a first region in which a polarity inversion layer is formed, and a second region in which the polarity inversion layer is not formed are provided on a substrate. Next, in a second step S102, a first nitride semiconductor is epitaxially grown on the substrate having the first region and the second region along the c-axis direction such that a first semiconductor layer is formed. Next, in a third step S103, a second nitride semiconductor is epitaxially grown on the first semiconductor layer along the c-axis direction such that a second semiconductor layer is formed on the first semiconductor layer. The second nitride semiconductor has different polarization, electron affinity, and band-gap energy from the first nitride semiconductor. The second semiconductor layer forms a heterojunction with the first semiconductor layer. The interface therebetween has a polarization charge, which is positive or negative depending on polarity.

Abstract: An antenna module includes: a substrate with at least the top surface being a single crystal of silicon carbide; a single-crystal graphene layer provided in contact with the top surface of the substrate; and a gallium nitride layer on the substrate. The antenna module is characterized in that an antenna element portion is formed by patterning a region in the graphene layer that is not covered by the gallium nitride layer, an active element portion is formed in the gallium nitride layer, and a connection portion connecting the antenna element portion and the active element portion are integrally formed.

Abstract: A Schottky barrier layer in separate regions between a source electrode and a gate electrode and between a drain electrode and the gate electrode is completely covered with an etching stopper layer. The gate electrode is separated from a cap layer.

Abstract: A Schottky barrier layer in separate regions between a source electrode and a gate electrode and between a drain electrode and the gate electrode is completely covered with an etching stopper layer. The gate electrode is separated from a cap layer.