Optical activation of Si and Ge nanowires codoping with Er:Yb rare earth by sol-gel methods

Si and Ge are both important semiconducting electronic materials with indirect band gap. Long length of their nanowires exceeding 1 μm, compared with the isolated nanocrystals, provides a very high areal density of Er ions. In addition, Yb ions are an useful sensitizer for the Er emission. Strong optical activations of Er-doped and Er:Yb-codoped SiNWs and GeNWs by sol-gel methods are observed. The photoluminescence (PL) intensity of Er-doped GeNWs is higher than that of Er-doped SiNWs. Furthermore, Yb ions greatly improved the PL intensity of Er:Yb-codoped GeNWs, but they has no effect on the PL intensity of Er:Yb-codoped SiNWs. These differences are mainly due to the indirect gap nature of Si and Ge semiconductor.