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Imaging Localized Energy States in Silicon-Doped InGaN Nanowires Using 4D Electron Microscopy
ACS Energy Letters ( IF 19.3 ) Pub Date : 2018-01-30 00:00:00 , DOI: 10.1021/acsenergylett.7b01330
Riya Bose 1 , Aniruddha Adhikari 1 , Victor M. Burlakov 2 , Guangyu Liu 3 , Md Azimul Haque 4 , Davide Priante 3 , Mohamed N. Hedhili 5 , Nimer Wehbe 5 , Chao Zhao 3 , Haoze Yang 1 , Tien Khee Ng 3 , Alain Goriely 2 , Osman M. Bakr 1 , Tom Wu 4 , Boon S. Ooi 3 , Omar F. Mohammed 1
Affiliation  

Introducing dopants into InGaN NWs is known to significantly improve their device performances through a variety of mechanisms. However, to further optimize device operation under the influence of large specific surfaces, thorough knowledge of ultrafast dynamical processes at the surface and interface of these NWs is imperative. Here, we describe the development of four-dimensional scanning ultrafast electron microscopy (4D S-UEM) as an extremely surface-sensitive method to directly visualize in space and time the enormous impact of silicon doping on the surface-carrier dynamics of InGaN NWs. Two time regimes of surface dynamics are identified for the first time in a 4D S-UEM experiment: an early time behavior (within 200 ps) associated with the deferred evolution of secondary electrons due to the presence of localized trap states that decrease the electron escape rate and a longer time scale behavior (several ns) marked by accelerated charge carrier recombination. The results are further corroborated by conductivity studies carried out in the dark and under illumination.

中文翻译:

使用4D电子显微镜对掺硅的InGaN纳米线中的局部能量状态进行成像

已知将掺杂剂引入InGaN NW中可通过多种机制显着改善其器件性能。但是,为了进一步优化在较大比表面的影响下的设备操作,必须全面了解这些NW的表面和界面处的超快速动力学过程。在这里,我们描述了二维扫描超快电子显微镜(4D S-UEM)的发展,这是一种非常表面敏感的方法,可以在空间和时间上直接可视化硅掺杂对InGaN NWs表面载流子动力学的巨大影响。在4D S-UEM实验中首次确定了两种表面动力学时间机制:由于存在局部陷阱能降低电子逸出速率,而二次电子延迟发展的早期行为(200 ps以内)与降低电子逸出速率有关,并且以加速电荷载流子重组为特征的时间尺度行为(几ns)。在黑暗和光照下进行的电导率研究进一步证实了该结果。
更新日期:2018-01-30
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