Enhanced Optoelectronic Performance of a Passivated Nanowire‐Based Device: Key Information from Real‐Space Imaging Using 4D Electron Microscopy. Issue 17 (3rd March 2016)

• Record Type: Journal Article
• Authors: Khan, Jafar I.; Adhikari, Aniruddha; Sun, Jingya; Priante, Davide; Bose, Riya; Shaheen, Basamat S.; Ng, Tien Khee; Zhao, Chao; Bakr, Osman M.; Ooi, Boon S.; Mohammed, Omar F.
• Is Part Of: Small. Volume 12:Issue 17(2016)
• Page Start: 2313
• Page End: 2320
• Publication Date: 2016-03-03
• Subjects: 4D ultrafast microscopy -- carrier recombination -- charge carrier dynamics -- InGaN nanowires -- passivation; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201503651
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract : Managing trap states and understanding their role in ultrafast charge‐carrier dynamics, particularly at surface and interfaces, remains a major bottleneck preventing further advancements and commercial exploitation of nanowire (NW)‐based devices. A key challenge is to selectively map such ultrafast dynamical processes on the surfaces of NWs, a capability so far out of reach of time‐resolved laser techniques. Selective mapping of surface dynamics in real space and time can only be achieved by applying four‐dimensional scanning ultrafast electron microscopy (4D S‐UEM). Charge carrier dynamics are spatially and temporally visualized on the surface of InGaN NW arrays before and after surface passivation with octadecylthiol (ODT). The time‐resolved secondary electron images clearly demonstrate that carrier recombination on the NW surface is significantly slowed down after ODT treatment. This observation is fully supported by enhancement of the performance of the light emitting device. Direct observation of surface dynamics provides a profound understanding of the photophysical mechanisms on materials' surfaces and enables the formulation of effective surface trap state management strategies for the next generation of high‐performance NW‐based optoelectronic devices. Abstract : Time‐resolved images (snapshots) using 4D scanning ultrafast microscopy clearly demonstrate that carrier recombination on semiconductor nanowires surface is significantly slowed after ODT surface treatment. This is supported by the better performance of devices based on these passivated materials, providing the first experimental evidence for the strong correlation between the carrier dynamics obtained selectively from materials surfaces and optoelectronic device performance.