From Impurity Doping to Metallic Growth in Diffusion Doping: Properties and Structure of Silver-Doped InAs Nanocrystals

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• 作者：Yorai Amit ; Yuanyuan Li ; Anatoly I. Frenkel ; Uri Banin
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：9
• 期：11
• 页码：10790-10800
• 全文大小：713K
• ISSN：1936-086X

文摘

Tuning of the electronic properties of presynthesized colloidal semiconductor nanocrystals (NCs) by doping plays a key role in the prospect of implementing them in printed electronics devices such as transistors and photodetectors. While such impurity doping reactions have already been introduced, the understanding of the doping process, the nature of interaction between the impurity and host atoms, and the conditions affecting the solubility limit of impurities in nanocrystals are still unclear. Here, we used a postsynthesis diffusion-based doping reaction to introduce Ag impurities into InAs NCs. Optical absorption spectroscopy and analytical inductively coupled plasma mass spectroscopy (ICP-MS) were used to present a two-stage doping model consisting of a 鈥渄oping region鈥?and a 鈥済rowth region鈥? depending on the impurity to NC ratio in the reaction vessel. X-ray absorption fine-structure (XAFS) spectroscopy was employed to determine the impurity location and correlate between the structural and electronic properties for different sizes of InAs NCs and dopant concentrations. The resulting structural model describes a heterogeneous system where the impurities initially dope the NC, by substituting for In atoms near the surface of the NC, until the 鈥渟olubility limit鈥?is reached, after which the rapid growth and formation of metallic structures are identified.