Correlation between electroluminescence and charge trapping in multi-color Eu implanted Si-based light-emitting diodes

Electroluminescence (EL) spectra, charge trapping during operation of EL devices and clustering of rare earth oxides in SiO2 have been investigated in Eu implanted SiO2-Si structures which demonstrate luminescence associated with the light-emitting transitions in Eu2+ and Eu3+. Strong electron trapping in all studied regions of the injected charge (from 1×1014 to 1×1018 e/cm2) during operation of the light-emitting devices has been found that it considerably differed from the oxides implanted by other rare earth impurities (Ce, Tb, Gd, Er, Tm). It has been shown that the observed strong electron trapping and the low EL intensity in the Eu implanted structures were associated with enhanced clustering of the Eu oxides. The mechanism of electron trapping in the SiO2 containing a large cluster concentration is discussed, and flash lamp annealing is proposed to decrease the nanocluster size and to enhance the EL intensity.