Patent ID: 8581106

Claim:
A submount comprising: a submount substrate, a substrate protective layer formed on the submount substrate, an electrode layer formed on the substrate protective layer, an adherent layer formed on the electrode layer, and a solder layer formed on the adherent layer wherein said submount substrate is made of a nitride ceramic essentially consisting of aluminum nitride, and carbon concentration in at least one of the region adjacent to an interface formed between said submount substrate and said substrate protective layer, the region adjacent to an interface formed between said substrate protective layer and said electrode layer, the region adjacent to an interface formed between said electrode layer and said adherent layer, and the region adjacent to an interface formed between said adherent layer and said solder layer is not more than 1×10 20 atoms/cm 3 ; the submount further comprising: said solder layer has a solder protective layer on said solder laver, wherein formed thereon and that carbon concentration in the region adjacent to an interface formed between said solder layer and said solder protective layer is not more than 1×10 20 atoms/cm 3 .