Park Young S, Kang Tae W, Taylor R A
Quantum Functional Semiconductor Research Center and Department of Physics, Dongguk University, Seoul 100-715, Korea.
Nanotechnology. 2008 Nov 26;19(47):475402. doi: 10.1088/0957-4484/19/47/475402. Epub 2008 Oct 29.
We have studied the photoluminescence properties of GaN nanorods grown on Si(111) substrates by radio-frequency plasma-assisted molecular-beam epitaxy. The hexagonal shaped nanorods with lateral average diameters from 30 to 150 nm are obtained by controlling the Ga flux with a fixed amount of nitrogen. As the diameters decrease, the main emission lines assigned as donor bound excitons are blueshifted, causing a spectral overlap of this emission line with that of the free exciton at 10 K due to the quantum size effect in the GaN nanorods. The temperature-dependent photoluminescence spectra show an abnormal behaviour with an 'S-like' shape for higher diameter nanorods. The activation energy of the free exciton for GaN nanorods with different diameters was also evaluated.
我们研究了通过射频等离子体辅助分子束外延在Si(111)衬底上生长的GaN纳米棒的光致发光特性。通过在固定量的氮气下控制Ga通量，获得了横向平均直径为30至150nm的六边形纳米棒。随着直径减小，归属于施主束缚激子的主要发射线发生蓝移，由于GaN纳米棒中的量子尺寸效应，导致该发射线在10K时与自由激子的发射线发生光谱重叠。温度依赖的光致发光光谱显示，对于直径较大的纳米棒，呈现出“S形”的异常行为。还评估了不同直径的GaN纳米棒中自由激子的激活能。
