Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China. Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, People's Republic of China.
Nanotechnology. 2013 Oct 11;24(40):405303. doi: 10.1088/0957-4484/24/40/405303. Epub 2013 Sep 12.
GaN nanorods with a period of 400 nm and diameter of 200 nm, and nano-gratings with a period of 400 nm and gap width of 100 nm are fabricated on wafers by a soft UV-curing nanoimprint lithography. These nanostructures show high periodicity and good morphology. The photoluminescence (PL) spectra exhibit that the integral PL intensity of GaN nanorods is enhanced as much as 2.5 times, compared to that of as-grown GaN films. According to finite-difference time-domain simulations and cathodoluminescence mappings, it is concluded that the enhancement for nanorods is due to the improvements of both spontaneous emission rate and light extraction efficiency caused by periodic GaN structures on the surface. By identifying the Raman shift of E1(TO) and E2(H) modes of GaN films with nano-gratings and nanorods, the normal-plane strain ε(zz) is determined. The PL emission energy is found to be proportional to the ε(zz), whose linear proportionality factor is calculated to be -27 meV GPa(-1).
通过软紫外光固化纳米压印光刻在晶圆上制造出周期为 400nm、直径为 200nm 的 GaN 纳米棒，以及周期为 400nm、间隙宽度为 100nm 的纳米光栅。这些纳米结构具有高周期性和良好的形态。光致发光（PL）谱表明，与未经处理的 GaN 薄膜相比，GaN 纳米棒的整体 PL 强度增强了 2.5 倍。根据有限差分时域模拟和阴极发光映射，得出增强的原因是由于表面周期性 GaN 结构引起的自发发射率和光提取效率的提高。通过识别具有纳米光栅和纳米棒的 GaN 薄膜的 E1（TO）和 E2（H）模式的拉曼位移，确定了法向平面应变 ε（zz）。发现 PL 发射能与 ε（zz）成正比，其线性比例因子计算为-27meV/GPa（-1）。
