Visualizing anisotropy in the surface oxidation of germanium by wet etching of patterned nanowedges: proof of concept

Abstract

We study the anisotropy in surface oxidation for Ge(100) and (110) in HCl/H2O2 solution complemented by synchrotron X-ray photoemission spectroscopy (SXPS) measurements integrated with an in situ etching chamber.

A synchrotron radiation photoelectron spectroscopy study on atomic-scale wet etching of InAs (111)-A and (111)-B in acidic peroxide solutions: surface chemistry versus kinetics

“…cm -2 min -1 ) showed a linear dependence on the concentration of the strong oxidizing agent H2O2. This linear feature is similar to previously reported nm-scale kinetics for GaAs, InGaAs, and Ge [19][20][49][50][51] and is typical for conditions where surface reactions are rate limiting. Anisotropy in the etching kinetics can be vividly seen for the two surface orientations.…”

“…The ICP-MS data (Figure 1) confirm a higher chemical stability for both InAs (111) orientations in HCl/ H2O2 solution. We attribute this observation to a chloride passivation that stabilizes the surface that is also observed for other III-V [19][20]65 and group IV [49][50][51] semiconductors. Furthermore, the (111)-B plane demonstrated the highest overall chemical reactivity in the studied acidic H2O2 solutions and a larger coverage of corresponding chloride and sulfate species (Figure S1, S3).…”

“…Surface chemistry and electronic structure of InAs (111)-A and (111)-B were analyzed by means of a highly surface sensitive synchrotron radiation X-ray photoemission spectroscopy (SXPS) directly connected with an etching chamber to exclude the detrimental effects of ambient O2 and H2O on the surface properties. [40][41][42][43][44][45][46][47][48][49][50] All experimental conditions (sample preparation, etching kinetics, and surface analysis) were described in Supplementary Information.…”

Investigation of Selective Wet Etching of SiGe Substrates for High-Performance Device Manufacturing

“…Other factors may affect the lateral etch rate. One is the difference in crystal orientation (blanket (001) vs. superlattice (110)) [14] and the difference in crystal quality. More work is needed to understand the effect of the structure and pH.…”