Electroluminescence from the light-emitting devices with erbium-doped SrTiO_3 films on oxidized silicon substrate

摘要

We report on the visible and near-infrared (NIR) electroluminescence (EL) from the light-emitting devices (LEDs) with erbium-doped SrTiO3 (SrTiO3:Er) films on oxidized silicon substrate, namely, with the structure of SrTiO3: Er/SiO2/Si in abbreviation. It is found that the 900 degrees C-annealed SrTiO3:Er films are most desirable for the SrTiO3: Er/SiO2/Si structured LEDs. In the EL-enabling voltage range, the electron transportation through the SiO2 layer of SrTiO3:Er/SiO2/Si structured LED is revealed to be compliant with the trap-assisted tunneling (TAT) mechanism. Based on the energy band diagram of the SrTiO3:Er/SiO2/Si structured LED under the EL-enabling forward bias where the negative voltage is connected with Si substrate, it is believed that a number of conduction electrons in Si can tunnel into the conduction band of SiO2 layer via the aforementioned TAT mechanism and then jump down to the conduction band of SrTiO3 host. Because the conduction band offset of SiO2 and SrTiO3 host is larger than 3 eV, the conduction electrons reaching the SrTiO3 host gain considerably high energies so that they become the so-called hot electrons. The Er3+ ions incorporated into the SrTiO3 host are impact-excited by the hot electrons, ultimately emanating the characteristic visible and NIR light.