Anttu N, Xu H Q
Division of Solid State Physics, Lund University, P. O. Box 118, S-221 00 Lund, Sweden.
J Nanosci Nanotechnol. 2010 Nov;10(11):7183-7. doi: 10.1166/jnn.2010.2907.
We present a theoretical study of the absorption of light in periodic arrays of InP nanowires. The absorption in the array depends strongly on the diameter and the length of the nanowires, as well as the period of the array. Nanowires of a length of just 2 microm are able, after an appropriate choice for the other parameters, to absorb more than 90% of the incident energy of TE and TM polarized light, with photon energies almost all the way down to the band gap energy and an incidence angle up to 50 degree. This high total absorption arises from a good coupling of the incident light into the nanowire array at the top interface between air and the array and absorption inside the array before the light reaches the interface between the nanowires and the substrate. We find that for a given photon energy there exists a critical nanowire diameter above which a dramatic increase in the absorption occurs. The critical diameter decreases for increasing photon energies, and is directly related to the dispersion of waveguiding modes in single isolated nanowires. A characterization showed that the absorption characteristics of the nanowire arrays are very promising for photovoltaic applications.
我们对磷化铟纳米线周期性阵列中的光吸收进行了理论研究。阵列中的吸收强烈依赖于纳米线的直径、长度以及阵列的周期。在对其他参数进行适当选择后，长度仅为2微米的纳米线能够吸收超过90%的TE和TM偏振光的入射能量，光子能量几乎一直低至带隙能量，入射角可达50度。这种高总吸收率源于在空气与阵列顶部界面处入射光与纳米线阵列的良好耦合，以及在光到达纳米线与衬底界面之前在阵列内部的吸收。我们发现，对于给定的光子能量，存在一个临界纳米线直径，超过该直径吸收会急剧增加。临界直径随光子能量增加而减小，并且与单个孤立纳米线中波导模式的色散直接相关。一项表征表明，纳米线阵列的吸收特性在光伏应用方面非常有前景。
