Loeto K, Kusch G, Brandt O, Coulon P-M, Hammersley S, Lähnemann J, Girgel I, Fairclough S M, Sarkar M, Shields P A, Oliver R A
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom.
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Berlin, Germany.
Nanotechnology. 2024 Oct 23;36(2). doi: 10.1088/1361-6528/ad8356.
This study examines the exciton dynamics in InGaN/GaN core-shell nanorods using time-resolved cathodoluminescence (TRCL), which provides nanometer-scale lateral spatial and tens of picoseconds temporal resolutions. The focus is on thick (>20 nm) InGaN layers on the non-polar, semi-polar and polar InGaN facets, which are accessible for study due to the unique nanorod geometry. Spectrally integrated TRCL decay transients reveal distinct recombination behaviours across these facets, indicating varied exciton lifetimes. By extracting fast and slow lifetime components and observing their temperature trends along with those of the integrated and peak intensity, the differences in behaviour were linked to variations in point defect density and the degree and density of localisation centres in the different regions. Further analysis shows that the non-polar and polar regions demonstrate increasing lifetimes with decreasing emission energy, attributed to an increase in the depth of localisation. This investigation provides insights into the intricate exciton dynamics in InGaN/GaN nanorods, offering valuable information for the design and development of optoelectronic devices.
本研究使用时间分辨阴极发光（TRCL）来研究InGaN/GaN核壳纳米棒中的激子动力学，TRCL可提供纳米级横向空间分辨率和数十皮秒的时间分辨率。研究重点是在非极性、半极性和极性InGaN晶面上的厚（>20 nm）InGaN层，由于独特的纳米棒几何结构，这些晶面便于进行研究。光谱积分TRCL衰减瞬态揭示了这些晶面上不同的复合行为，表明激子寿命各不相同。通过提取快速和慢速寿命成分，并观察它们的温度趋势以及积分强度和峰值强度的温度趋势，将行为差异与不同区域中点缺陷密度、局域中心程度和密度的变化联系起来。进一步分析表明，非极性和极性区域的寿命随着发射能量的降低而增加，这归因于局域深度的增加。这项研究为InGaN/GaN纳米棒中复杂的激子动力学提供了见解，为光电器件的设计和开发提供了有价值的信息。
