Interface Effects at Semiconductor Homojunctions

The possibility of creating band offsets at polar semiconductor homojunctions by means of intralayers of atomic-like thickness has been demonstrated using photoemission spectroscopy with synchrotron radiation. Al-P and Ga-P double layers at Si homojunctions, as well as Si intralayers at GaAs homojunctions have been studied, and experimental evidence of creation of band offsets as large as 0.3-0.4 eV has been found in both cases. Recent theoretical models can explain the existence and the direction of the discontinuity, but overestimate its amount and cannot explain its saturation at low intralayer thickness. Our experiments prove that it is possible to produce band discontinuities at junctions between two semiconductors using only interface effects.