GaAs(111)A and B in hydrazine sulfide solutions : extreme polarity dependence of surface adsorption processes

TL;DR

This study investigates how surface polarity influences chemical adsorption processes on GaAs(111)A and B surfaces treated with hydrazine sulfide, revealing extreme polarity-dependent differences in surface chemistry.

Contribution

It demonstrates the polarity-dependent adsorption mechanisms on GaAs(111) surfaces using synchrotron photoemission spectroscopy, highlighting the distinct chemical modifications on A and B surfaces.

Findings

B surface arsenic replaced by nitrogen atoms

A surface covered by sulfur bonded to gallium

Adsorption processes depend strongly on surface polarity

Abstract

Chemical bonds formed by hydrazine-sulfide treatment of GaAs(111) were studied by synchrotron photoemission spectroscopy. At the B surface, the top arsenic atoms are replaced by nitrogen atoms, while GaAs(111)A is covered by sulfur, also bonded to underlying gallium, despite the sulfide molar concentration being 103 times smaller than that of the hydrazine. This extreme dependence on surface polarity is explained by competitive adsorption processes of HS- and OH- anions and of hydrazine molecules, on Ga- adsorption sites, which have distinct configurations on the A and B surfaces.