Photoluminescence Probing of Complex H2O Adsorption on InGaN/GaN Nanowires

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• 作者：Konrad Maier ; Andreas Helwig ; Gerhard Müller ; Pascal Hille ; Jörg TeubertMartin Eickhoff
• 刊名：Nano Letters
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：17
• 期：2
• 页码：615-621
• 全文大小：521K
• ISSN：1530-6992

文摘

We demonstrate that the complex adsorption behavior of H₂O on InGaN/GaN nanowire arrays is directly revealed by their ambient-dependent photoluminescence properties. Under low-humidity, ambient-temperature, and low-excitation-light conditions, H₂O adsorbates cause a quenching of the photoluminescence. In contrast, for high humidity levels, elevated temperature, and high excitation intensity, H₂O adsorbates act as efficient photoluminescence enhancers. We show that this behavior, which can only be detected due to the low operation temperature of the InGaN/GaN nanowires, can be explained on the basis of single H₂O adsorbates forming surface recombination centers and multiple H₂O adsorbates forming surface passivation layers. Reversible creation of such passivation layers is induced by the photoelectrochemical splitting of adsorbed water molecules and by the interaction of reactive H₃O⁺ and OH^– ions with photoactivated InGaN surfaces. Due to electronic coupling of adsorbing molecules with photoactivated surfaces, InGaN/GaN nanowires act as sensitive nanooptical probes for the analysis of photoelectrochemical surface processes.