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首页> 外文期刊>Journal of Physics, D. Applied Physics: A Europhysics Journal >A HIGH-RESOLUTION, ANALYTICAL STUDY OF THE ANODIC FILM FORMED ON GAAS IN A TUNGSTATE ELECTROLYTE
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A HIGH-RESOLUTION, ANALYTICAL STUDY OF THE ANODIC FILM FORMED ON GAAS IN A TUNGSTATE ELECTROLYTE

机译：钨酸盐电解质上GAAS阳极氧化膜的高分辨率分析研究

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The anodic film formed in aqueous tungstate electrolyte at 2.5 A m(-2), to about 295 nm thickness, on n(+)-type GaAs at high faradaic efficiency, about 94%, has been examined by analytical transmission electron microscopy, using ultramicrotomed film sections, Rutherford backscattering spectroscopy, x-ray photoelectron spectroscopy, electron probe micro-analysis and scanning electron microscopy. The film is revealed to be amorphous and to comprise a uniform distribution of units of Ga2O3 and As2O3 across the main film thickness, with possible gallium enrichment in the outermost 10 nm or so of the film. Gallium and arsenic are incorporated into the anodic film at the alloy/film interface in the substrate proportions, without development of a layer enriched either in gallium or in arsenic just beneath the anodic film. The formation ratio for the film is about 2.01 nm V-1. The film, formed by migration both of cations and of anions across its thickness, is enriched in arsenic relative to the substrate composition, the level of enrichment suggesting that Ga3+ ions migrate outwards in the film about 2.4 times faster than do As3+ ions, based on a cation transport number of 0.2. The Ga3+ ions may be ejected, to the electrolyte, under the electric field, on reaching the film/electrolyte interface, with limited formation of an outer layer of essentially Ga2O3 at the film/electrolyte interface, or form a layer of Ga2O3, up to about 10% of the total film thickness, which is thinned after anodizing by exposure to the electrolyte and the rinse water. Significantly, the outer layer of film material developed by the faster migrating Ga3+ ions prevents loss of As3+ ions from the film during film growth. However, during prolonged exposure to aqueous conditions in the absence of the field, the film becomes enriched in gallium species due to preferential dissolution of arsenic species. The high faradaic efficiency of film growth is a consequence of the presence of a tungsten-enriched layer, probably a gel composed of hydrated tungsten oxide, which develops at the film/electrolyte interface during film growth. No significant presence of tungsten species within the bulk of the anodic film is detected. [References: 48]
机译：使用分析型透射电子显微镜检查了使用2.5％m（-2）钨酸盐电解质在n（+）型GaAs上以约94％的高法拉第效率在n（+）型GaAs上形成的阳极膜。超薄切片切片，卢瑟福背散射光谱，X射线光电子能谱，电子探针显微分析和扫描电子显微镜。揭示该膜是无定形的，并且包括Ga 2 O 3和As 2 O 3的单元在整个主膜厚度上的均匀分布，并且可能在膜的最外约10nm处富集镓。镓和砷在基体比例的合金/膜界面处掺入到阳极膜中，而没有在阳极膜下方形成富含镓或砷的层。膜的形成比率为约2.01nm V-1。由阳离子和阴离子在整个厚度方向上迁移形成的薄膜相对于基质成分富含砷，富集水平表明，Ga3 +离子在薄膜中向外迁移的速度比As3 +离子快约2.4倍。阳离子传输数为0.2。当到达膜/电解质界面时，在电场作用下，Ga3 +离子可被喷射到电解质中，在膜/电解质界面处形成基本为Ga2O3的外层，或形成一层Ga2O3，直至约占总膜厚的10％，在阳极氧化后通过暴露于电解质和冲洗水中而变薄。重要的是，由较快迁移的Ga3 +离子形成的薄膜材料外层可防止薄膜生长过程中As3 +离子从薄膜中流失。然而，在没有场地的情况下长时间暴露于水性条件下，由于砷物质的优先溶解，该膜富含镓物质。膜生长的高法拉第效率是存在富钨层的结果，该富钨层可能是由水合氧化钨组成的凝胶，它在膜生长过程中在膜/电解质界面处形成。在阳极膜的主体中没有检测到明显的钨物种。 [参考：48]

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