Sharvani S, Upadhayaya Kishor, Kumari Gayatri, Narayana Chandrabhas, Shivaprasad S M
Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India.
Nanotechnology. 2015 Nov 20;26(46):465701. doi: 10.1088/0957-4484/26/46/465701. Epub 2015 Oct 26.
The GaN nanowall network, formed by opening the screw dislocations by kinetically controlled MBE growth, possesses a large surface and high conductivity. Sharp apexed nanowalls show higher surface electron concentration in the band-tail states, in comparison to blunt apexed nanowalls. Uncapped silver nanoparticles are vapor deposited on the blunt and sharp GaN nanowall networks to study the morphological dependence of band-edge plasmon-coupling. Surface enhanced Raman spectroscopy studies performed with a rhodamine 6G analyte on these two configurations clearly show that the sharp nanowall morphology with smaller Ag nanoparticles shows higher enhancement of the Raman signal. A very large enhancement factor of 2.8 × 10(7) and a very low limit of detection of 10(-10) M is observed, which is attributed to the surface plasmon resonance owing to the high surface electron concentration on the GaN nanowall in addition to that of the Ag nanoparticles. The significantly higher sensitivity with same-sized Ag nanoparticles confirms the unconventional role of morphology-dependent surface charge carrier concentration of GaN nanowalls in the enhancement of Raman signals.
通过动力学控制分子束外延生长打开螺旋位错形成的氮化镓纳米壁网络具有大表面积和高导电性。与钝尖纳米壁相比，尖顶纳米壁在带尾态中显示出更高的表面电子浓度。将未封装的银纳米颗粒气相沉积在钝尖和尖顶的氮化镓纳米壁网络上，以研究带边等离子体耦合的形态依赖性。用罗丹明6G分析物对这两种构型进行的表面增强拉曼光谱研究清楚地表明，具有较小银纳米颗粒的尖顶纳米壁形态显示出更高的拉曼信号增强。观察到非常大的增强因子2.8×10(7)和非常低的检测限10(-10)M，这归因于除银纳米颗粒外，氮化镓纳米壁上高表面电子浓度引起的表面等离子体共振。相同尺寸银纳米颗粒时显著更高的灵敏度证实了氮化镓纳米壁形态依赖的表面电荷载流子浓度在拉曼信号增强中的非常规作用。
