Structure and method of structure in which a contact, e.g., low resistance; ohmic; resulting in Schottky isolation, is coupled to a doped region that is buried in a substrate. In a bipolar transistor having a collector region formed below an upper surface of a substrate, a trench is formed through a portion of the collector region, and the sidewall(s) and/or bottom of the trench are doped, e.g., by ion implantation or dopant. The trench is filled with a conductor, e.g., a refractory metal such as tungsten.