Estrin Y, Rich D H, Rozenfeld N, Arad-Vosk N, Ron A, Sa'ar A
Department of Physics and The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O.B 653, Beer-Sheva 84105, Israel.
Nanotechnology. 2015 Oct 30;26(43):435701. doi: 10.1088/0957-4484/26/43/435701. Epub 2015 Oct 5.
The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ∼2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ω(sp), and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals.
利用时间分辨阴极发光（CL）探测了多层硅纳米晶体（SiNCs）上银、金和铝薄膜的自发发射率（SER）增强情况。SiNCs通过等离子体增强化学气相沉积生长在Si(100)上。通过薄金属膜注入脉冲高能电子束，在金属覆盖的SiNCs中产生电子 - 空穴对，这被发现是对激光或光激发不透明的等离子体量子异质结构和纳米结构的理想激发方法。使用空间、光谱和时间分辨的CL来测量同一样品中金属覆盖区域和裸露区域的SiNCs的激子寿命。相对于裸露样品的SER，观察到金属覆盖的SiNCs的SER增强归因于SiNC激子与薄金属膜的表面等离激元极化激元（SPP）的耦合。在55K温度下，分别观察到Ag、Au和Al薄膜的SER最大增强约为2.0、1.4和1.2。所选择的三种等离子体金属Ag、Au和Al有助于对表面等离激元能量ω(sp)与SiNC激子发射能量之间存在不同差异的金属薄膜的激子 - SPP耦合进行有趣的比较。进行了珀塞尔增强因子Fp的温度依赖性建模，其中包括金属介电特性的温度依赖性。
