Terahertz emission from ZnSe nano-dot surface

The 19th International Symposium on Space Terahertz Technology

Shan Hea ; b ; Xiaoshu Chena ; Xiaojun Wua ; Fuli Zhaoa ; Reng Wang c ; Weizheng Fang c ; Shuhong Hu c ; Ning Dai c ; *Gang Wanga

Others  :  http://www.nrao.edu/meetings/isstt/papers/2008/2008546000.pdf
PID  :  3771

来源: CEUR

【 摘 要 】

As shown in Figure 1 (Fig. 1) ZnSe nano dots are fabricated on the surface of <111> orientationZnSe using femtosecond laser ablation technique. In this work, we studied the THz generation propertiesof the ZnSe nano-dots by electro-optic detection configuration. Three THz radiation mechanisms areobserved in experiments: current surge effect (drift current), Photo Dember effect (diffusion current) andoptical rectification. Compared with bulk ZnSe, the ZnSe nano dots generated much higher THz radiationpower at the same experimental condition. When the ZnSe nano-dots covered 10% of total radiationsurface, the radiation power is about two times stronger than that from the bulk bare sample (Fig. 2). Basicly, there are two kinds of mechanisms occur predominantly for the THz radiation of ZnSe nanodots: the first is lighting-rod effect that fields tend to concentrate at the tips of protrusions on surface; thesecond is local-plasmon effect that collective oscillation of electrons occurs in these protrusions. Thesetwo effects make the total surface electric field largely enhanced. In this study, we attribute the THzradiation enhancement phenomenon of ZnSe nano dots to the surface field enhancement effect. Using asimple hemispheriod model, we also obtained the enhancement factor of ZnSe nano dots.