Kinetics of GaAs Dissolution in H₂O₂−NH₄OH−H₂O Solutions

Abstract

GaAs, a compound semiconductor commonly used in optoelectronic devices, is often subjected to wet-etching techniques during microelectronic device manufacture. In this work we investigated the wet etching of GaAs by H2O2−NH4OH−H2O solutions using a batch stirred-tank reactor and determined the intrinsic kinetics of the dissolution reaction. Increasing the NH4OH content produced a constant rate above a minimum concentration. The reaction rate was found, in the presence of excess NH4OH, to fit a rate equation r = k[H2O2]0.75 at 15, 25, and 40 °C with an activation energy of 33.7 kJ/mol. Using NaOH instead of NH4OH resulted in greatly reduced reaction rates, and it was concluded that the presence of the ammonium ion increases the rate by forming soluble compounds with oxidized species of Ga and As. Analysis of the surface by X-ray photon spectroscopy confirmed that samples etched in solutions containing NH4OH had considerably less oxide content on the surface than that etched in H2O2−H2O only. NH4OH does not directly react with GaAs but incorporates a second step into the overall etch reaction, facilitating the oxidation by H2O2 and the formation of soluble compounds.

Observation of surface enhanced IR absorption coefficient in alkanethiol based self-assembled monolayers on GaAs(001)

“…FAX: ͑819͒ 821-7937. canethiol ͑n17͒, hexadecanethiol ͑n15͒, tetradecanethiol ͑n13͒, dodecanethiol ͑n11͒, and decanethiol ͑n9͒, where the decade prefix refers to n + 1 carbon atoms per molecule, accounting for the terminal CH 3 group. In addition, 50-100 mM of 28% NH 4 OH/ H 2 O was added to each solution, according to sample preparation procedures described by McGuiness et al 7 The GaAs wafers were then wet etched in 28% NH 4 OH/ H 2 O for 2 min in order to remove surface oxides 7,24,25 followed by direct rinsing in degassed ethanol and subsequent immersion in the prepared solutions for 20 h. Following SAM-GaAs incubation, the samples were rinsed in IPA and dried in a nitrogen stream. 26 Liquid phase samples of n9, n11, and n13 were prepared by wetting the neat liquid between two thin ͑150 m͒ coverglass slides.…”

Palladium–gallium intermetallic compounds for the selective hydrogenation of acetylenePart II: Surface characterization and catalytic performance

“…Ammonia solution is well-known for chemical etching of semiconductors like GaAs [37][38][39]. Chemical etching, however, may result in the formation of neighboring Pd atoms and, thus, Pd clusters or Pd overlayers by dissolution of Ga from the bulk structure of the PdGa intermetallic compounds.…”

Etching of the intermetallic compounds PdGa and Pd3Ga7: An effective way to increase catalytic activity?

“…Chemical etching with ammonia solution was employed to remove the gallium oxide overlayer from the surface of the intermetallic particles. Ammonia solutions are well known for chemical etching of semiconductor surfaces like GaAs [18][19][20]. Chemical etching of PdGa and Pd 3 Ga 7 was per-formed at room temperature with an aqueous ammonia solution at pH values as indicated.…”