SPECTRAL-ANALYSIS OF ELECTROLUMINESCENCE FROM SIO2 UNDER FOWLER-NORDHEIM TUNNELING CONDITIONS

Electroluminescence from thermally grown SiO2 has been examined during Fowler-Nordheim current injection. SiO2 thicknesses ranging from 8.0 to 23.5 nm were studied under varying stress currents. Peak photon counts were observed at 2.5 eV (500 rim) for SiO2 thickness in the range of 15.0 to 23.5 nm and at 1.4 eV (900 nm) for the 8.0 nm samples. Photon emission increased as a function of cumulative charge injection in the 15.0 to 23.5 nm thickness range. This phenomenon was correlated to electron trapping in the oxide as evidenced by I-V charge-trapping measurements. These results are compared with previous electroluminescence studies and a model is proposed based on radiative recombination from traps located 2.0-2.5 eV from the SiO2 conduction band. In contrast to thick oxides, the primary source of emission from the 8.0-run samples may be electron-hole pair recombination in the bulk following injection through the oxide. The lack of interaction with SiO2 trapping centers in the 8.0-nm SiO2 is due to the long mean-free path of electrons relative to the SiO2 thickness.