Single p-type, GaAs crystals of high purity, Zn doped, were used to determine whether or not the inverse octahedral {111} faces show potential differences and various rates of anodic dissolution. The Ga{111}, As{111}, {110}, and {100} faces, were polished, etched, and etch-polished with concentrated H2SO4 + H2O2, and immersed in IN KOH. The Ga{111} faces were found to be the most noble with respect to rest and anodic dissolution potentials. The potential difference between the inverse {111} faces was as large as 0.14v for the rest and 0.123v for the dissolution potentials. The 4 anodic polarization curves gave nearly parallel Tafel lines, with a slope of 66.0 ± 1 mv/log i, up to current densities of 0.5 ma/cm2. The rate of anodic dissolution of the As{111} faces was 69 X as high as the inverse Ga{111}. The activation energies of dissolution of all 4 faces were equal within experimental limits: 16.7 ± 0.7 kcal mole−1. It is concluded that the slow step in the dissolution of GaAs is a one electron discharge with subsequent steps leading to the formation of Ga(OH)3 to provide a protective coating not readily soluble in KOH. From this point of view all observed phenomena can be explained in a qualitative manner. © 1968, The Electrochemical Society, Inc. All rights reserved.


Materials Science and Engineering

Second Department


International Standard Serial Number (ISSN)

1945-7111; 0013-4651

Document Type

Article - Journal

Document Version


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Publication Date

01 Jan 1968