SYSTHESIS AND OPTICAL PROPERTIES OF RARE EARTHS DOPED NANO-SEMICONDUCTORS AND THEIR APPLICATIONS

Abstract

Er and Yb have been doped into nanocrystalline Si and ZnO thin films. Sharp and intense photoluminescence (PL) lines related to intra-4f transitions in the rare earth ions were observed. The optical transition dynamics of the rare earth ions were investigated by time-resolved PL measurements. It was demonstrated that a nano-meter sizing of Si widened the energy bandgap and led to an increase of doping densities of the rare earths. It was also shown that the Er-related PL gave rise to different features under direct and indirect excitations indicating a strong interaction of electron-hole pairs in the host with 4f electrons in the rare earth ions. A co-doping effect of Yb and Er into nanocrystalline Si was presented also. Our results suggested a rare earth-rare earth coupling between the Yb 3+ ions and the Er 3+ ions, which transferred the energy from Yb to Er and enhanced the 1.54 μm PL of Er.