Abstract: According to one embodiment, a semiconductor device includes: a first insulating element and a second insulating element each controlled based on a control signal; a first control circuit configured to control selection of one of the first insulating element and the second insulating element based on the control signal; a first switch element; a second switch element; a second control circuit configured to control the first switch element based on an output of the first insulating element; and a third control circuit configured to control the second switch element based on an output of the second insulating element.

Abstract: According to one embodiment, a semiconductor device includes a substrate; a first transistor, a second transistor, a third transistor, and a fourth transistor; a first light emitting element and a second light emitting element; a first light receiving element configured to switch the first transistor and the second transistor to an ON state or to an OFF state; and a second light receiving element configured to switch the third transistor and the fourth transistor to the ON state or to the OFF state, wherein the first light emitting element and the second light emitting element are configured such that, when either one of the first light emitting element or the second light emitting element is turned to a lit state, the other one is turned to an unlit state.

Abstract: A semiconductor light emitting element includes a semiconductor substrate including a first region of a first conductivity type. A first semiconductor layer of a second conductivity type is disposed on a first surface of the semiconductor substrate. A second semiconductor layer of the first conductivity type is disposed on the first semiconductor layer with a light emitting layer between the first and second semiconductor layer. A first electrode connects electrically to the first semiconductor layer and a second electrode electrically connects to the second semiconductor layer. A third electrode including a metal is on a second surface of the semiconductor substrate that is opposite the first surface.