Abstract: A semiconductor device includes: a channel layer not containing Al; a barrier layer above the channel layer containing Al; a recess; and an ohmic electrode in the recess, which is in ohmic contact with a two-dimensional electron gas layer. An Al composition ratio distribution of the barrier layer has a maximum point at a first position. The semiconductor device includes: a first inclined surface of the barrier layer which includes the first position and is in contact with the ohmic electrode; and a second inclined surface of the barrier layer which intersects the first inclined surface on a lower side of the first inclined surface, and is in contact with the ohmic electrode. To the surface of the substrate, an angle of the second inclined surface is smaller than an angle of the first inclined surface. A position of the first intersection line is lower than the first position.

Abstract: A semiconductor device for power amplification includes: a source electrode, a drain electrode, and a gate electrode disposed above a semiconductor stack structure including a first nitride semiconductor layer and a second nitride semiconductor layer; and a source field plate that is disposed above the semiconductor stack structure between the gate electrode and the drain electrode, and has a same potential as a potential of the source electrode. The source field plate has a staircase shape, and even when length LF2 of an upper section is increased for electric field relaxation, an increase in parasitic capacitance Cds generated between the source field plate and a 2DEG surface is inhibited.

Abstract: A semiconductor device includes: a channel layer not containing Al; a barrier layer above the channel layer containing Al; a recess; and an ohmic electrode in the recess, which is in ohmic contact with a two-dimensional electron gas layer. An Al composition ratio distribution of the barrier layer has a maximum point at a first position. The semiconductor device includes: a first inclined surface of the barrier layer which includes the first position and is in contact with the ohmic electrode; and a second inclined surface of the barrier layer which intersects the first inclined surface on a lower side of the first inclined surface, and is in contact with the ohmic electrode. To the surface of the substrate, an angle of the second inclined surface is smaller than an angle of the first inclined surface. A position of the first intersection line is lower than the first position.

Abstract: A semiconductor device includes a substrate; a first nitride semiconductor layer above the substrate; a second nitride semiconductor layer on the first nitride semiconductor layer; an ohmic electrode above the substrate; and a contact layer in contact with at least a part of the ohmic electrode, the contact layer containing silicon and chlorine. The second nitride semiconductor layer has a wider band gap than the first nitride semiconductor layer. A two-dimensional electron gas channel is formed in the first nitride semiconductor layer at a heterointerface between the first nitride semiconductor layer and the second nitride semiconductor layer. A silicon concentration has a higher peak value than a chlorine concentration in the contact layer.

Abstract: A semiconductor device includes a substrate; a first nitride semiconductor layer above the substrate; a second nitride semiconductor layer on the first nitride semiconductor layer; an ohmic electrode above the substrate; and a contact layer in contact with at least a part of the ohmic electrode, the contact layer containing silicon and chlorine. The second nitride semiconductor layer has a wider band gap than the first nitride semiconductor layer. A two-dimensional electron gas channel is formed in the first nitride semiconductor layer at a heterointerface between the first nitride semiconductor layer and the second nitride semiconductor layer. A silicon concentration has a higher peak value than a chlorine concentration in the contact layer.

Abstract: It is intended to provide an optical disk apparatus which detects a light amount greater than zero even when used in conjunction with an optical disk substrate having a large birefringence, so that it is possible to properly read a signal without errors and properly perform optical disk controls. The optical disk apparatus includes: a light source for emitting light; an objective lens for converging the light onto a signal surface of an optical disk; a polarized beam diffraction element for diffracting the light reflected from the optical disk; a photodetector for detecting the light diffracted from the polarized beam diffraction element; and a wavelength plate disposed between the optical disk and the polarized beam diffraction element.

Abstract: It is intended to provide an optical disk apparatus which detects a light amount greater than zero even when used in conjunction with an optical disk substrate having a large birefringence, so that it is possible to properly read a signal without errors and properly perform optical disk controls. The optical disk apparatus includes: a light source for emitting light; an objective lens for converging the light onto a signal surface of an optical disk; a polarized beam diffraction element for diffracting the light reflected from the optical disk; a photodetector for detecting the light diffracted from the polarized beam diffraction element; and a wavelength plate disposed between the optical disk and the polarized beam diffraction element.

Abstract: It is intended to provide an optical disk apparatus which detects a light amount greater than zero even when used in conjunction with an optical disk substrate having a large birefringence, so that it is possible to properly read a signal without errors and properly perform optical disk controls. The optical disk apparatus includes: a light source for emitting light; an objective lens for converging the light onto a signal surface of an optical disk; a polarized beam diffraction element for diffracting the light reflected from the optical disk; a photodetector for detecting the light diffracted from the polarized beam diffraction element; and a wavelength plate disposed between the optical disk and the polarized beam diffraction element.