A semiconductor device includes two semiconductor chips that are interposed between a pair of radiation members, and thermally and electrically connected to the radiation members. Tips are formed on the fiber segments that have a radius substantially small by exposing the tips to a reactive liquid for a duration of time The tips are coated with a low work function conducting material to form emitters. Each superlattice may include a plurality of stacked groups of layers, with each group including a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and at least one non-semiconductor monolayer thereon.