Doping interface dipoles: Tunable heterojunction barrier heights and band-edge discontinuities by molecular beam epitaxy.

We have succeeded for the first time in artificially tuning the conduction and valence band barrier heights at an abrupt intrinsic semiconductor- semiconductor heterojunction via a doping interface dipole (DID). This is achieved by means of ultrathin ionized donor and acceptor sheets in situ grown within ~ 100angstroms from the hetero-interface by molecular beam epitaxy.