Nanoscale etching of III-V semiconductors in acidic hydrogen peroxide solution : GaAs and InP, a striking contrast in surface chemistry

In this study of nanoscale etching for state-of-the-art device technology, the importance of surface chemistry, in particular the nature of the surface oxide, is demonstrated for two III-V materials. Striking differences in etching kinetics were found for GaAs and InP in sulphuric and hydrochloric acidic solutions containing hydrogen peroxide. Under similar conditions, etching of GaAs was much faster, while the dependence of the etch rate on pH, and on H2O2 and acid concentrations also differed markedly for the two semiconductors. Surface analysis techniques provided information on the product layer present after etching: strongly non-stoichiometric porous (hydr)oxides on GaAs and a thin stoichiometric oxide that forms a blocking layer on InP. Reaction schemes are provided that allow one to understand the results, in particular the marked difference in etch rate and the contrasting role of chloride in the dissolution of the two semiconductors. A critical factor in determining the surface chemistry is considered to be the ease with which a proton can be removed from the group V hydroxide, which is formed in the initial etching step (the breaking of the III-V surface bond).peerReviewe

Nanoscale etching of III-V semiconductors in acidic hydrogen peroxide solution: GaAs and InP, a striking contrast in surface chemistry

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Epitaxial Defects in Nanoscale InP Fin Structures Revealed by Wet-Chemical Etching

In this work, we report on wet-chemical defect revealing in InP fin structures relevant for device manufacturing. Both HCl and HBr solutions were explored using bulk InP as a reference. A distinct difference in pit morphology was observed between the two acids, attributed to an anisotropy in step edge reactivity. The morphology of the etch pits in bulk InP suggests that the dislocations are oriented mainly perpendicular to the surface. By studying the influence of the acid concentration on the InP fin recess in nanoscale trenches, it was found that aqueous HCl solution was most suitable for revealing defects. Planar defects in InP fin structures grown by the aspect ratio trapping technique could be visualized as characteristic shallow grooves approximately one nanometer deep. It is challenging to reveal defects in wide-field InP fins. In these structures, dislocations also reach the surface next to stack faults or twinning planes. Due to the inclined nature, dislocation-related pits are only a few atomic layers deep. Extending the pits is limited by the high reactivity of the fin sides and the strong surface roughening during etching. The process window for revealing wet-chemical defects in InP fins is limited

Wet Chemical Processing of Ge in Acidic H(2)O(2)Solution: Nanoscale Etching and Surface Chemistry

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Atomic-scale investigations on the wet etching kinetics of GeversusSiGe in acidic H(2)O(2)solutions: a postoperandosynchrotron XPS analysis

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