Enhancement in the efficiency of light emission from silicon by a thin Al2O3 surface-passivating layer grown by atomic layer deposition at low temperature

Thin Al2O3 surface-passivating layers grown by atomic layer deposition at 100 degrees C were demonstrated to be instrumental in producing efficient light emission from silicon. External quantum efficiency up to 1.3x10(-4) was observed from silicon metal-insulator-semiconductor light-emitting diodes with a 5 nm Al2O3 surface-passivating layer as the insulator, which is more than tenfold that from similar devices with a 5 nm SiO2 insulator layer thermally oxidized at 1000 degrees C. Anomalous temperature dependences of the photoluminescence intensities and spectra at low temperatures indicate the presence of bound excitonic traps at the Al2O3/Si interface. The enhanced light emission may be attributed to the temporary capture of excitons by the interfacial bound excitonic traps, which effectively reduces nonradiative recombination. (c) 2007 American Institute of Physics.