Photoluminescence and probe effect of Er-doped nanometer-sized Si materials

Er was doped into porous Si and nanocrystalline Si thin films. Sharp and intense photoluminescence at 1.54 μm was observed up to room temperature. We demonstrate that Er3+ ions are excited by an energy transfer process from the excited electron-hole pairs in the host materials and no direct excitation of Er3+ ions can be observed. This fact suggests that the Er emission could be used as a probe to determine absorption edges of the hosts. This idea was first applied to Er-doped porous Si. Identical excitation edges of the 1.54 μm emission and the visible emission from porous Si have been demonstrated. We suggest that the method should also be valid for measuring the absorption edge of a nanometer-sized Si host material even if it is not luminescent.