Homojunction Band Discontinuities Induced by Dipolar Intralayers - Al-As in Ge

The possibility of inducing a band offset in the electronic structure of Ge homojunctions has been recently demonstrated using Ga-As double layers. A photoemission study is presented in which it is proved that a similar effect can be induced using Al-As as an intralayer. Specifically, an offset of 0.4 eV has been obtained. It is found that the cation-anion intralayer deposition sequence produces the same dipole as the anion-cation sequence. This result is similar to that found for large overlayer coverages in the case of Ga-As intralayers; but contrary to the Ga-As intralayers the present system does not exhibit a reversed discontinuity for small thicknesses.