Nitride semiconductor element, nitride semiconductor light emitting element, ultraviolet light emitting element

A nitride semiconductor light emitting element comprising:

• a substrate;
• a first Group III nitride semiconductor layer containing at least aluminum (Al) and gallium (Ga);
• a nitride semiconductor body formed on part of the first Group III nitride semiconductor layer and containing a Group III nitride semiconductor active layer containing at least aluminum (Al) and gallium (Ga), a carrier blocking layer as an AlxGa(1-x)N(0.90≤x≤1.00) layer, and a second Group III nitride semiconductor layer in this order from a side of the substrate;
• a first electrode layer formed on the first Group III nitride semiconductor layer;
• and
• a second electrode layer formed on the second Group III nitride semiconductor layer,
• wherein:
• the first electrode layer contains one or more first regions and one or more second regions,
• a composition of the one or more first regions is different from a composition of the one or more second regions,
• the one or more first regions and the one or more second regions contact the first Group III nitride semiconductor layer at a contact surface,
• each first region of the first electrode layer comprises an alloy containing aluminum, the alloy being present at or within 3 nm of a contact surface to the first Group III nitride semiconductor layer of the first electrode layer,
• the one or more second regions do not extend over a top surface of any of the one or more first regions,
• a third region is disposed over one of the second regions, wherein a composition of the third region is different from the composition of the one or more first regions and different from the composition of the one or more second regions,
• in plan view, at least one first region is surrounded by the one of the second regions,
• in plan view, the at least one first region is surrounded by the third region, and
• a total existence ratio of the one or more first regions and the one or more second regions at or within 3 nm of the contact surface is 70% by area or more.