Atomic-Structure-Dependent Adsorption of Ammonia onto GaAs(111)B Surfaces

Abstract

Adsorption of ammonia, which is the initial stage of the vapor phase epitaxial growth of nitride semiconductors, is examined by using pulsed-ammonia-beam scatterings from differently reconstructed GaAs(111)B surfaces. It is found that the surface atomic structure of GaAs(111)B surface more strongly influences the ammonia adsorption than that of GaAs(100) surface. Incident ammonia molecules are temporarily trapped in a deep precusor state on a (√ 19×√ 19)R23.4° surface, while they are desorbed without such a surface trapping from an As-excess (2×2) surface. On the other hand, ammonia is efficiently stuck on a Ga-rich (1×1) surface, which is probably related to the efficient surface decomposition of ammonia under a specific condition of nitride epitaxy. The results are discussed on the basis of the atomic arrangement of the reconstructed surface.

Interfacial Anodic Behaviors of n- and p-GaAs Semiconductors in Liquid Ammonia at 223 K

“…The surface gallium atoms of GaAs act as Lewis acids. [28][29][30][31][32] Their largely empty dangling bonds should be the favored bonding sites for ammonia molecule adsorption first, then to radical species issued from ammonia oxidation, e.g., NH 2…”

“…The surface gallium atoms of GaAs act as Lewis acids. [28][29][30][31][32] Their largely empty dangling bonds should be the favored bonding sites for ammonia molecule adsorption first, then to radical species issued from ammonia oxidation, e.g., NH 2 • , NH • , N • . The linear relation established between the scan rate and the anodic peak intensity favors this assumption.…”

The pH response of the InP/liquid ammonia interface at 223K: A pure nernstian behavior

“…The interaction of gaseous ammonia with cleaved GaAs surface had been already investigated, and the atomic arrangement of the reconstructed surface was discussed [23]. At room temperature, chemisorption of gaseous ammonia had been already studied onto p-GaAs using scanning tunneling microscopy (STM) [21]. Atomic-resolution images wholly agree with the prediction of Lewis acid-base chemistry at the interface semiconductor/ammonia.…”

“…Solid state physic studies also provide an additional approach to analyze the interface semiconductor III-V/NH 3 through essentially spectroscopic data [17,20,21]. The interaction of gaseous ammonia with cleaved GaAs surface had been already investigated, and the atomic arrangement of the reconstructed surface was discussed [23].…”

“…As a result, from chemical properties of ammonia and solid state studies, ammonia molecules are able to keep its polarity properties at the interface NH 3 /III-V semiconductors [21][22][23]. Ammonia molecules can be adsorbed onto a bare InP surface at room temperature as shown by Salmagne et al [22].…”