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Engineering Graphene Quantum Dots for Enhanced Ultraviolet and Visible Light p-Si Nanowire-Based Photodetector
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2017-08-21 00:00:00 , DOI: 10.1021/acsami.7b07667
Iuliana Mihalache 1 , Antonio Radoi 1 , Razvan Pascu 1 , Cosmin Romanitan 1, 2 , Eugenia Vasile 1, 3 , Mihaela Kusko 1
Affiliation  

In this work, a significant improvement of the classical silicon nanowire (SiNW)-based photodetector was achieved through the realization of core–shell structures using newly designed GQDPEIs via simple solution processing. The poly(ethyleneimine) (PEI)-assisted synthesis successfully tuned both optical and electrical properties of graphene quantum dots (GQDs) to fulfill the requirements for strong yellow photoluminescence emission along with large band gap formation and the introduction of electronic states inside the band gap. The fabrication of a GQDPEI-based device was followed by systematic structural and photoelectronic investigation. Thus, the GQDPEI/SiNW photodetector exhibited a large photocurrent to dark current ratio (Iph/Idark up to ∼0.9 × 102 under 4 V bias) and a remarkable improvement of the external quantum efficiency values that far exceed 100%. In this frame, GQDPEIs demonstrate the ability to arbitrate both charge-carrier photogeneration and transport inside a heterojunction, leading to simultaneous attendance of various mechanisms: (i) efficient suppression of the dark current governed by the type I alignment in energy levels, (ii) charge photomultiplication determined by the presence of the PEI-induced electron trap levels, and (iii) broadband ultraviolet-to-visible downconversion effects.

中文翻译:

用于增强的紫外线和可见光p-Si纳米线光电探测器的工程石墨烯量子点

在这项工作中,通过使用新设计的GQD PEI通过简单的溶液处理实现核-壳结构,实现了对基于经典硅纳米线(SiNW)的光电探测器的重大改进。聚乙烯亚胺(PEI)辅助合成成功地调节了石墨烯量子点(GQDs)的光学和电学性质,从而满足了强黄色光致发光的要求,并形成了较大的带隙并在带隙内引入了电子态。在制造了基于GQD PEI的设备之后,进行了系统的结构和光电研究。因此,GQD PEI / SiNW光电探测器表现出大的光电流与暗电流之比(I ph/高达~0.9×10 2下为4V偏压),外部量子效率的值远远超过100%的显着改善。在此框架中,GQD PEI证明了能够仲裁异质结内部的电荷载流子光生和输运的能力,从而导致同时出现各种机制:(i)有效抑制暗电流,该暗电流由能级中的I型排列控制, (ii)由PEI诱导的电子陷阱能级确定的电荷光电倍增,以及(iii)宽带紫外到可见光下转换效应。
更新日期:2017-08-21
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