Replacement emitter for reduced contact resistance

Device structures for a bipolar junction transistor and methods for fabricating such device structures. An emitter structure is formed that has a semiconductor layer with a top surface defining a recess and a sacrificial layer comprised of a disposable material in the recess. A contact opening is formed that extends through one or more first dielectric layers to the sacrificial layer. After the contact opening is formed, the sacrificial layer is removed from the recess. Alternatively, the layer in the recess may be comprised of a non-disposable material that may occupy the recess at the time that a contact is formed in the contact opening.