On the selective etching of In0.53Ga0.47As and In0.72Ga0.28As0.61P0.39 vs.InP in alkaline K3Fe(CN)(6) solutions - An electrochemical study

To get insight into the selective etching of In0.53Ga0.37As and In(0.72)G(0 .28)As(0.61)P(0.39) with respect to InP in alkaline K3Fe(CN)(6)-containing solutions, the electrochemical and etching properties of Zn0.53Ga0.47As and In0.72Ga0.28As0.61P0.39 were studied by rotating (ring)-disk voltammetry a nd by electrical impedance and etch rate measurements. It is shown that bot h In0.53Ga0.47As and In0.72Ga0.28As0.61P0.39 are etched by K3Fe(CN)(6) in a n electroless etching process, in which holes are injected by K3Fe(CN)(6) a nd consumed in the anodic dissolution. The observed selectivity in the etch ing of In0.53Ga0.47As and In0.72Ga0.28As0.61P0.39 vs. InP is due to a diffe rence in valence band-edge position, which determines the hole injection ra te. Furthermore, it was found that a mechanism of galvanic element formatio n enhances the selectivity when InP and In(0.53)G(0.47)As or InP and In0.72 Ga0.28As0.61P0.39 are in electrical contact. (C) 1999 The Electrochemical S ociety. S0013-4651(98)02-039-4. All rights reserved.