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°C were demonstrated to be instrumental in producing efficient light emission from silicon. External quantum efficiency up to 1.3×10−4 was observed from silicon metal-insulator-semiconductor light-emitting diodes with a 5nm Al2O3 surface-passivating layer as the insulator, which is more than tenfold that from similar devices with a 5nm SiO2 insulator layer thermally oxidized at 1000°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.