The dependence of the morphology of macropores in p‐type silicon electrodes on formation parameters such as substrate doping density, electrolyte composition, and applied current density is investigated. The results are compared with the well‐understood case of electrochemical macropore formation on n‐type silicon electrodes. A growth model is derived in which pore formation is shown to be a consequence of charge‐transfer mechanisms in a Schottky diode applied to a nonplanar interface. © 1999 The Electrochemical Society. All rights reserved.

Despite the importance of scientific inquiry in science education, researchers and educators disagree considerably regarding what features define this instructional approach. While a large body of literature addresses theoretical considerations, numerous empirical studies investigate scientific inquiry on quite different levels of detail and also on different theoretical grounds. Here, only little systematic research has analysed the different conceptualisations and usages of the overarching construct of scientific inquiry in detail. To close this gap, a review of the research literature on scientific inquiry was conducted based on a widespread approach to defining scientific inquiry as activities that students engage in. The main goal is to provide a systematic overview about the range and spectrum of definitions and operationalisations used with regard to single activities of the inquiry process in empirical studies. The findings from the review first and foremost illustrate the variability in the ways these activities have been operationalised and implemented. For each activity, studies differ significantly not only with respect to the focus, explicitness and comprehensiveness of their operationalisations but also with regard to the consistency of their implementation in the form of instructional or interventional components in the study and/or in the focus of the assessment of student performance. This has significant implications regarding the validity and comparability of results obtained in different studies, e.g. in the context of discussions concerning the effectiveness of inquiry-based instruction. In addition, the interrelation between scientific inquiry, scientific knowledge and the nature of science seems to be underexplored. The conclusions make the case for further theoretical work as well as empirical research.

The dependence of macropore morphology on the orientation of p-and n-type silicon samples was studied for various organic and aqueous electrolytes containing hydrofluoric acid. Scanning electron microscopy was used studying the morphology of the macropores. The results show that the macropore formation in p-and n-type silicon is a strongly anisotropic process. Depending on the substrate orientation ͗100͘ and ͗113͘ preferred growth directions could be observed. The microstructure of macropores was studied by analytical and high-resolution transmission electron microscopy. The surface of macropores in n-and p-type Si͑001͒ shows ͕111͖ facets indicating that ͕111͖ planes are stabilized against further dissolution. Breakthrough pores show very specific anisotropic properties independent of the electrolyte. These pores consist of periodic arrangements of truncated octahedral voids with ͕111͖ walls strung up in ͗100͘ directions. The crystal orientation dependence of pore formation reflects specific properties of the pore formation mechanism and one of the important electrolyte parameters is the ability to form an anodic oxide. Macropores formed in more strongly oxidizing electrolytes tend to have smoother macropore walls.

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