Shigeo Sugawara and Naoharu Kamada
Department of Materials Science and Engineering, Faculty of Engineering and Resource Science, Akita University, Akita 010-8502
Anodic dissolution of n-GaP (111) surfaces at high voltages in aqueous KOH solutions is an effective method of electropolishing the surfaces to remove damage induced by mechanical polishing. However, anodic dissolution at certain high voltages causes the formation of whiskers at dislocation sites. As such a phenomenon is peculiar, it is necessary to systematically investigate the behavior of the dissolution under varying experimental conditions. Therefore, we carried out a series of anodic dissolutions of n-GaP (111) surfaces in aqueous NaOH solutions. The morphology of the anodically dissolved surfaces was observed by optical microscopy and scanning electron microscopy. When the surface is dissolved at 16 V for 1.8 × 103 s in a 0.2 kmol/m3 NaOH solution, there is marked whisker nucleation at dislocation sites on the surface. Dissolutions at 20-30 V in 0.2-0.5 kmol/m3 NaOH solutions produce smooth surfaces; however, microscopic pits are detected on the electropolished surfaces by atomic force microscopy.
gallium phosphide, single crystal, wafer, sodium hydroxide solution, anodic dissolution, pit, whisker, dislocation, microscopy
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