Coupled shallow impurity states in a freestanding semiconductor nanowire and in a semiconductor nanowire surrounded by a metallic gate are studied within the effective-mass approximation. Bonding and antibonding states are found due to the coupling of the two impurities, and their energy converges with increasing distance $d_i$ between the two impurities. The dependences of the binding energy on the wire radius $R$, the distance $d_i$ between the two impurities, and the impurity radial position in the nanowire are examined.

• Received 25 April 2008

DOI:https://doi.org/10.1103/PhysRevB.79.085306