FERMI-LEVEL-PINNING-INDUCED IMPURITY REDISTRIBUTION IN SEMICONDUCTORS DURING EPITAXIAL-GROWTH

The influence of Fermi-level pinning at a semiconductor surface on dopant distribution is demonstrated. It is shown that surface-induced Fermi-level-pinning results in impurity drift during crystal growth by molecular-beam epitaxy. The surface electric field can be screened and reversed by appropriate background doping. Secondary-ion mass spectroscopy measurements indicate a drastic decrease of Si surface drift in AlxGa1-xAs upon screening of the dipole interaction. Reversal of the surface electric field results in a migration of Be impurities in GaAs away from the surface toward the substrate during epitaxial growth. © 1990 The American Physical Society.