Electrically driven luminescence of nanocrystalline Si/SiO2 multilayers on various substrates

Amorphous-Si:H/SiO2 multilayers were fabricated on various substrates by alternatively changing the ultra-thin amorphous Si films deposition and in situ plasma oxidation processes. Uniform silicon nanodots with controllable size were formed by combining the rapid thermal annealing and furnace annealing techniques as revealed by cross-sectional transmission electron microscopy. Light-emitting diodes based on Al/(nc-Si/SiO2) multilayers/Si substrate/Al structures were fabricated and electrically driven luminescence was demonstrated at room temperature. It was found that the substrate had a significant impact on the carrier injection efficiency and the luminescence intensity. The turn-on voltages of the device on p+-Si and p-Si substrate were 2.2 and 8 V, respectively. Meanwhile, electroluminescence intensity of the device on p+-Si substrate was five times higher than that on p-Si substrate under the same power supply, which means the heavily doped substrate is helpful for enhancing the carrier injection efficiency.