A method of forming a metal semiconductor alloy on a fin structure that includes forming a semiconductor material layer of a polycrystalline crystal structure material or amorphous crystal structure material on a fin structure of a single crystal semiconductor material, and forming a metal including layer on the semiconductor material layer. Metal elements from the metal including layer may then b intermixed metal elements with the semiconductor material layer to provide a metal semiconductor alloy contact on the fin structure. A core of the fin structure of the single crystal semiconductor material is substantially free of the metal elements from the metal including layer.