5 Search Results

Potassium hydroxide (KOH) aqueous solutions can effectively etch germanium. Etch rates were determined in an electrolytic etch cell. Electrically isolated Ge wafers were subject to an etch rate of 1.45 ± 0.07 nm min ⁻¹ , increasing to 12.6 ± 0.2 nm min ⁻¹ when grounded, 97 ± 2 nm min ⁻¹ when biased at −0.9 V, and 138 ± 2 nm min ⁻¹ with periodic biasing. Results suggest that the previously reported limited etching in KOH is associated with the recombination of holes with electrons injected from the surface reaction. The results of this study demonstrate that changing themore » hole concentration through biasing is an effective tool to control electrolytic etch rates, enabling future selective etching processes for germanium.« less

Anodic electrolytic etching of germanium has been performed in hydrogen peroxide etchants with controlled external conditions. In-situ current and ex-situ etch-depths were measured and tracked with respect to etchant composition and stir rates. Gas bubbles formed during the etching process were found to cause non-uniformity in etch-current and surface quality. The effects were minimized in specific composition spaces. Quantitative analysis revealed a linear correlation of the number of electrons transferred during germanium oxidation with the number of surface atoms removed. Experimental results of 2.77 electrons/atom deviate significantly from 4 electrons/atom previously reported for silicon. The conclusion is that etching mechanismsmore » for germanium are sufficiently different from those for silicon which invalidates the direct transfer of processing techniques between the two materials.« less

Abstract Understanding interactions between externally applied electric fields and the interfacial structures of nanoscale ceramics is important for controlling their functional properties. In ceramic oxides, functional properties are determined by oxygen vacancy concentrations near and within grain‐boundary core structures. In this study it is shown that the application of electrostatic fields ranging from 0 to nominally 170 V/cm during diffusion bonding of bicrystals alters the atomic and electronic core structures of (100) twist grain boundaries in SrTiO ₃ . The applied electric field strength affects local oxygen vacancy concentrations and ordering of the oxygen sublattice. Results for this model system indicatemore » that electrostatic fields applied during ceramic manufacturing can be employed as a new processing parameter to tailor defect structure configurations and obtain unprecedented ceramic microstructures. The ability to manipulate interface configurations with electric fields in the absence of any sintering additives may have far reaching implications for tuning polarization and band structures in electroceramics while avoiding effects of often unwanted dopants.« less