Ultraviolet Reflective Rough Adhesive Contact

A device comprising:

• an active region configured to sense or emit ultraviolet light;
• a first semiconductor layer formed on a p-type side of the active region;
• a contact to the first semiconductor layer;
• a second p-type semiconductor layer located between the first semiconductor layer and the contact, wherein an interface between the second semiconductor layer and the contact includes a first roughness profile with a characteristic height and a characteristic width, wherein the characteristic height is an average vertical distance between adjacent crests and valleys of the first roughness profile and is between 3 and 20 nanometers, and wherein the characteristic width is an average lateral distance between adjacent crests and valleys of the first roughness profile and is within a range of approximately 0.1 micron to approximately fifty microns.

A device comprising:

• a first semiconductor layer formed of a first group III nitride material;
• a contact to the first semiconductor layer, wherein an interface between the first semiconductor layer and the contact includes a first roughness profile having a characteristic height between 3 and 20 nanometers and a characteristic width within a range of approximately 0.1 micron to approximately 50 microns;
• and
• an interlayer located between the first semiconductor layer and the contact, wherein the interlayer comprises a plurality of islands each having a closed boundary that is separate from the first semiconductor layer and the contact, wherein a first portion of the plurality of islands comprise a metal-based alloy having a high adhesion to group III nitride materials and a second portion of the plurality of islands comprise a metal to provide a low specific resistance contact to group III nitride materials.