Abstract: A device includes a semiconductor substrate containing gallium nitride and having a crystal face inclined from 0.05° to 15° inclusive with respect to the c-plane. The semiconductor substrate includes an irregular portion on the crystal face, and the contact angle of pure water having a specific resistance of 18 M?·cm or more on the surface of the irregular portion is 10° or less.

Abstract: A liquid treatment apparatus for treating water to be treated, according to the present disclosure, includes a treatment tank, a dielectric partition wall dividing inside of the treatment tank into a first space in which the water to be treated is injected, and a second space in which an electrolytic solution is filled, a first electrode at least part of which is arranged in the first space of the treatment tank, a second electrode at least part of which is arranged in the second space of the treatment tank, and a power supply that applies a high-frequency AC voltage between the first electrode and the second electrode.

Abstract: A liquid treatment method according to an aspect of the present disclosure comprises: starting application of a power between a pair of electrodes to generate plasma, which causes active species to be produced in a liquid; measuring the hydrogen ion concentration in the liquid while the plasma is generated; measuring a time elapsed after the starting the application of the power; and stopping the application of the power when a value calculated by (a) multiplying the hydrogen ion concentration by the elapsed time or (b) integrating the hydrogen ion concentration with respect to the elapsed time is larger than a first threshold.

Abstract: A liquid treatment unit includes: a treatment tank provided with an inlet and an outlet, the treatment tank having a shape that allows a portion of liquid to be retained; a controller that controls supply of liquid into the treatment tank and ejection of liquid from the treatment tank; and a plasma generator generates plasma in the liquid inside the treatment tank. The plasma generator generates plasma while the controller stops supply of liquid and ejection of liquid. After the liquid has been treated, the controller resumes the supply of liquid, and causes the liquid to be ejected from the treatment tank while allowing a portion of the treated liquid to be retained inside the treatment tank.

Abstract: A device includes a semiconductor substrate containing gallium nitride and having a crystal face inclined from 0.05° to 15° inclusive with respect to the c-plane. The semiconductor substrate includes an irregular portion on the crystal face, and the contact angle of pure water having a specific resistance of 18 M?·cm or more on the surface of the irregular portion is 10° or less.

Abstract: A liquid treatment apparatus includes a dielectric tube through which water to be treated flows, a first electrode, at least one end of which is dispose in the dielectric tube, and a second electrode made of a conductive metallic material, at least one end of the second electrode being disposed in the dielectric tube and on an upstream side of a flow pass of the water relative to the first electrode. The conductive metallic material of the second electrode is adapted to be in direct contact with the water to be treated. The liquid treatment apparatus also includes a power supply for applying a voltage between the first electrode and the second electrode, and a heat-resistant member covering at least a portion of an inner wall face of the dielectric tube. The portion of the inner wall faces the first electrode.

Abstract: A liquid treatment unit includes: a treatment tank provided with an inlet and an outlet, the treatment tank having a shape that allows a portion of liquid to be retained; a controller that controls supply of liquid into the treatment tank and ejection of liquid from the treatment tank; and a plasma generator generates plasma in the liquid inside the treatment tank. The plasma generator generates plasma while the controller stops supply of liquid and ejection of liquid. After the liquid has been treated, the controller resumes the supply of liquid, and causes the liquid to be ejected from the treatment tank while allowing a portion of the treated liquid to be retained inside the treatment tank.

Abstract: A liquid treatment apparatus includes a dielectric tube through which water to be treated flows, a first electrode at least a part of which is disposed in the dielectric tube, a second electrode at least a part of which is disposed in the dielectric tube at a position upstream of the first electrode, a gas supplier operative to generate a bubble by supplying a gas into the water to be treated, and a power supply operative to apply a voltage between the first electrode and the second electrode in a state in which the bubble covers a conductor-exposed portion of the first electrode.

Abstract: A liquid treatment apparatus according to the present disclosure includes a dielectric tube that defines a channel through which water to be treated flows, the channel being split upstream of the dielectric tube into a first channel and a second channel, the first channel and the second channel being merged with each other downstream of the dielectric tube, a first electrode at least partially disposed within the first channel, a second electrode at least partially disposed within the first channel, a first gas-supply unit that supplies gas to form a gas bubble into water to be treated that flows through the first channel, and a first power-supply that applies a voltage between the first electrode and the second electrode.

Abstract: The present disclosure provides a liquid treatment device, a liquid treatment method, and a plasma treatment liquid each capable of efficiently generating plasma and treating a liquid in a short time period. A liquid treatment device according to the present disclosure includes a first electrode, a second electrode disposed in a liquid to be treated, an insulator disposed around the first electrode with a space between the first electrode and the insulator, the insulator has an opening portion in a position in contact with the liquid to be treated, a power supply that applies voltage between the first electrode and the second electrode, and a supply device supplying a liquid to the space before the power source applies the voltage.

Abstract: A liquid treatment method according to an aspect of the present disclosure comprises: starting application of a power between a pair of electrodes to generate plasma, which causes active species to be produced in a liquid; measuring the hydrogen ion concentration in the liquid while the plasma is generated; measuring a time elapsed after the starting the application of the power; and stopping the application of the power when a value calculated by (a) multiplying the hydrogen ion concentration by the elapsed time or (b) integrating the hydrogen ion concentration with respect to the elapsed time is larger than a first threshold.

Abstract: A method according to an aspect of the present disclosure includes filtering plasma-treated water containing hydrogen peroxide which has been produced by generation of plasma in or near water; and applying ultrasound to the plasma-treated water after the filtering.

Abstract: A nitride semiconductor light emitting chip includes: a conductive substrate including a nitride semiconductor layer; an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer sequentially formed on a principal surface of the nitride semiconductor layer; and an n-side electrode formed in contact with the conductive substrate. A recess is formed in a back surface of the conductive substrate opposite to the principal surface. The n-side electrode is in contact with at least part of a surface of the recess. A depth D1 is not less than 25% of a thickness T, where T represents a thickness of the conductive substrate, and D1 represents a depth of the recess.

Abstract: In a structure including a gallium nitride-based semiconductor having an m-plane as a principal plane, and a metal layer provided on the principal plane, the principal plane has an n-type conductivity. An interface between the gallium nitride-based semiconductor and the metal layer contains oxygen. The metal layer includes a crystal grain extending form a lower surface to an upper surface of the metal layer.

Abstract: A nitride semiconductor light-emitting element includes: n-side and p-side electrodes; n-type and p-type nitride semiconductor layers; and an active layer arranged between the n- and p-type nitride semiconductor layers. The p-type nitride semiconductor layer has a projection having a height of 30 nm to 50 nm. The projection is formed of a p-type nitride semiconductor including magnesium and silicon. The p-type nitride semiconductor has a silicon concentration of 1.0×1017 cm?3 to 6.0×1017 cm?3. The projection projects from the active layer toward the p-side electrode. On a plan view of the nitride semiconductor light-emitting element, the p-side electrode overlaps with the projection. The projection includes a dislocation. The projection is surrounded with a flat surface which is formed of the p-type nitride semiconductor. And the projection has a higher dislocation density than the flat surface.

Abstract: A nitride-based semiconductor light-emitting element includes a substrate and a nitride semiconductor multilayer structure. The nitride semiconductor multilayer structure includes a nitride semiconductor active layer which emits polarized light. Angle ?, which is formed by at least one of the plurality of lateral surfaces of the substrate with respect to the principal surface of the substrate, is greater than 90°. Angle ?2 (mod 180°), which is an absolute value of an angle which is formed by an intersecting line of at least one of the plurality of lateral surfaces of the substrate and the principal surface of the substrate with respect to a polarization direction in the principal surface of the polarized light, is an angle which does not include 0° or 90°.

Abstract: A liquid treatment apparatus includes a dielectric tube through which water to be treated flows, a first electrode at least a part of which is disposed in the dielectric tube, a second electrode at least a part of which is disposed in the dielectric tube at a position upstream of the first electrode, a gas supplier operative to generate a bubble by supplying a gas into the water to be treated, and a power supply operative to apply a voltage between the first electrode and the second electrode in a state in which the bubble covers a conductor-exposed portion of the first electrode.

Abstract: The present disclosure provides a liquid treatment device, a liquid treatment method, and a plasma treatment liquid each capable of efficiently generating plasma and treating a liquid in a short time period. A liquid treatment device according to the present disclosure includes a first electrode, a second electrode disposed in a liquid to be treated, an insulator disposed around the first electrode with a space between the first electrode and the insulator, the insulator has an opening portion in a position in contact with the liquid to be treated, a power supply that applies voltage between the first electrode and the second electrode, and a supply device supplying a liquid to the space before the power source applies the voltage.

Abstract: A nitride semiconductor light-emitting element 300 is a nitride semiconductor light-emitting element which has a multilayer structure 310, the multilayer structure 310 including an active layer which is made of an m-plane nitride semiconductor. The multilayer structure 310 has a light extraction surface 311a which is parallel to an m-plane in the nitride semiconductor active layer 306 and light extraction surfaces 311b which are parallel to a c-plane in the nitride semiconductor active layer 306. The ratio of an area of the light extraction surfaces 311b to an area of the light extraction surface 311a is not more than 46%.

Abstract: A liquid treatment apparatus according to the present disclosure includes a dielectric tube that defines a channel through which water to be treated flows, the channel being split upstream of the dielectric tube into a first channel and a second channel, the first channel and the second channel being merged with each other downstream of the dielectric tube, a first electrode at least partially disposed within the first channel, a second electrode at least partially disposed within the first channel, a first gas-supply unit that supplies gas to form a gas bubble into water to be treated that flows through the first channel, and a first power-supply that applies a voltage between the first electrode and the second electrode.