Communication—Controlling Etching of Germanium through Surface Charge Manipulation

Abstract

Potassium hydroxide (KOH) aqueous solutions can effectively etch germanium. Etch rates were determined in an electrolytic etch cell. Electrically-isolated Ge wafers were subjected to an etch rate of 1.45±0.07 nm/min, increasing to 12.6±0.2 nm/min when grounded, 97±2 nm/min when biased at -0.9 V, and 138±2 nm/min with periodic biasing. Results suggest that 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 the hole concentration through biasing is effective for controlling electrolytic etch rates, enabling future selective etching processes for germanium.