A semiconductor layered body includes: a plurality of protrusions having first main surfaces along a reference plane and protruding from the reference plane; and a first semiconductor layer disposed at a side of the plurality of protrusions opposite to the first main surfaces so as to connect the plurality of protrusions to one another. Each of the protrusions is composed of a group III nitride that has a dislocation density of less than or equal to 110.sup.8 cm.sup.3, that is expressed by a composition formula of Al.sub.xGa.sub.1-xN, and that satisfies 0x<1. The first semiconductor layer is composed of a group III nitride that has a dislocation density of less than or equal to 110.sup.9 cm.sup.3, that is expressed by a composition formula of Al.sub.yGa.sub.1-yN, and that satisfies 0<y1.

A semiconductor layered body includes: a plurality of protrusions having first main surfaces along a reference plane and protruding from the reference plane; and a first semiconductor layer disposed at a side of the plurality of protrusions opposite to the first main surfaces so as to connect the plurality of protrusions to one another. Each of the protrusions is composed of a group III nitride that has a dislocation density of less than or equal to 110.sup.8 cm.sup.3, that is expressed by a composition formula of Al.sub.xGa.sub.1-xN, and that satisfies 0x<1. The first semiconductor layer is composed of a group III nitride that has a dislocation density of less than or equal to 110.sup.9 cm.sup.3, that is expressed by a composition formula of Al.sub.yGa.sub.1-yN, and that satisfies 0<y1.

A light emitting device includes: a light emitting element; a light-transmissive member including a first lower surface an outer periphery of which being located on an outer side of the light extraction surface in a plan view, an upper surface having a greater area than an area of the first lower surface, a first lateral surface connected to the upper surface, a second lateral surface positioned on an inner side of the first lateral surface and connected to the first lower surface, and a second lower surface connected to the first and second lateral surfaces; a light guiding member covering at least a portion of a lateral surface of the light emitting element and at least a portion of the second lateral surface and the second lower surface; and a covering member covering the first lateral surface and a lateral surface of the light guiding member.

A light emitting device includes: a light emitting element; a light-transmissive member including a first lower surface an outer periphery of which being located on an outer side of the light extraction surface in a plan view, an upper surface having a greater area than an area of the first lower surface, a first lateral surface connected to the upper surface, a second lateral surface positioned on an inner side of the first lateral surface and connected to the first lower surface, and a second lower surface connected to the first and second lateral surfaces; a light guiding member covering at least a portion of a lateral surface of the light emitting element and at least a portion of the second lateral surface and the second lower surface; and a covering member covering the first lateral surface and a lateral surface of the light guiding member.

A light-emitting device includes a substrate comprising a base member, a first wiring, a second wiring, and a via hole; at least one light-emitting element electrically connected to and disposed on the first wiring; and a covering member having light reflectivity and covering a lateral surface of the light-emitting element and a front surface of the substrate. The base member defines a plurality of depressed portions separated from the via hole in a front view and opening on a back surface and a bottom surface of the base member. The substrate includes a third wiring covering at least one of inner walls of the plurality of depressed portions and electrically connected to the second wiring. A depth of each of the plurality of depressed portions defined from the back surface toward the front surface is larger on a bottom surface side than on an upper surface side of the base member.

A light-emitting device includes a substrate comprising a base member, a first wiring, a second wiring, and a via hole; at least one light-emitting element electrically connected to and disposed on the first wiring; and a covering member having light reflectivity and covering a lateral surface of the light-emitting element and a front surface of the substrate. The base member defines a plurality of depressed portions separated from the via hole in a front view and opening on a back surface and a bottom surface of the base member. The substrate includes a third wiring covering at least one of inner walls of the plurality of depressed portions and electrically connected to the second wiring. A depth of each of the plurality of depressed portions defined from the back surface toward the front surface is larger on a bottom surface side than on an upper surface side of the base member.

An optical sensor includes a flexible substrate, a light emitting element, and a light receiving element. The light emitting element and the light receiving element are mounted on element mounting portions and connected to element connection portions by wires. The optical sensor also includes through wirings extending through the substrate. Each through wiring is bonded to the element mounting portion or the element connection portion. The through wirings include a heat radiation through wiring that is located immediately below the light emitting element and bonded to the element mounting portion on which the light emitting element is mounted. The optical sensor further includes light shielding materials and encapsulation resins for surrounding and encapsulating the light emitting element and the light receiving element, respectively.

An optical sensor includes a flexible substrate, a light emitting element, and a light receiving element. The light emitting element and the light receiving element are mounted on element mounting portions and connected to element connection portions by wires. The optical sensor also includes through wirings extending through the substrate. Each through wiring is bonded to the element mounting portion or the element connection portion. The through wirings include a heat radiation through wiring that is located immediately below the light emitting element and bonded to the element mounting portion on which the light emitting element is mounted. The optical sensor further includes light shielding materials and encapsulation resins for surrounding and encapsulating the light emitting element and the light receiving element, respectively.

A method for driving a light emitting device is provided. The light emitting device includes an anode, a cathode, a light emitting layer disposed between the anode and the cathode, and a hole transporting layer disposed between the anode and the light emitting layer. The hole transporting layer includes a cross-linked body of a crosslinkable material. According to the method, the light emitting device is driven by pulse voltage in which a first voltage not lower than the light emission start voltage of the light emitting device and a second voltage lower than the light emission start voltage of the light emitting device are alternately switched. A light emitting apparatus equipped with the light emitting device and a driving apparatus which drives the light emitting device by pulse voltage is also provided.

A method for driving a light emitting device is provided. The light emitting device includes an anode, a cathode, a light emitting layer disposed between the anode and the cathode, and a hole transporting layer disposed between the anode and the light emitting layer. The hole transporting layer includes a cross-linked body of a crosslinkable material. According to the method, the light emitting device is driven by pulse voltage in which a first voltage not lower than the light emission start voltage of the light emitting device and a second voltage lower than the light emission start voltage of the light emitting device are alternately switched. A light emitting apparatus equipped with the light emitting device and a driving apparatus which drives the light emitting device by pulse voltage is also provided.