Upadhyaya Kishor, S Sharvani, Ayachit Narasimha, Shivaprasad S M
Thin Films Lab, Centre for Materials Science, Department of Physics, B. V. Bhoomaraddi College of Engineering and Technology (Presently known as K. L. E. Technological University) Hubballi - 580031 India.
Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore-560064 India
RSC Adv. 2019 Sep 10;9(49):28554-28560. doi: 10.1039/c9ra04097h. eCollection 2019 Sep 9.
A hybrid system consisting of Ag nanoparticles dispersed onto a GaN nanowall network (GaN NWN) exhibited characteristic optical properties and electronic band structure. Surface-sensitive XPS studies of this high-surface-area system revealed the presence of a high surface charge carrier concentration due to dangling bonds, which resulted in a high metal-like surface conductivity. The low coverage of absorbed Ag led to the nanocluster formation, facilitating charge transfer from GaN to Ag, and thereby further increasing the surface charge carriers. Photoluminescence studies revealed the presence of a high density of band tail states at the conduction band, which is significantly (14-fold) larger than in the GaN epilayer. Raman studies show an increase (2.46-fold) in the interfacial strain at the Ag/GaN interface after the deposition of the Ag nanoparticles. We show that these surface modifications increase the density of hot spots, resulting in an intense Raman signal with an enhancement factor of 10. The role of the charge transfer between Ag nanoparticles and GaN NWN in the enhancement of Raman signal has been demonstrated.
一种由分散在氮化镓纳米壁网络（GaN NWN）上的银纳米颗粒组成的混合系统表现出独特的光学性质和电子能带结构。对这种高表面积系统进行的表面敏感X射线光电子能谱（XPS）研究表明，由于悬空键的存在，表面电荷载流子浓度很高，这导致了类似金属的高表面电导率。吸附的银覆盖率较低导致纳米团簇形成，促进了电荷从GaN转移到Ag，从而进一步增加了表面电荷载流子。光致发光研究表明，导带处存在高密度的带尾态，其数量比GaN外延层中的显著多（14倍）。拉曼研究表明，在沉积银纳米颗粒后，Ag/GaN界面处的界面应变增加（2.46倍）。我们表明，这些表面修饰增加了热点密度，产生了增强因子为10的强拉曼信号。已经证明了银纳米颗粒与GaN NWN之间的电荷转移在拉曼信号增强中的作用。
