μ-Watt Enhanced Electroluminescent Power of Silicon Nanocrystal Light-Emitting Diodes Made on Nano-Scale Silicon-Tip-Array Substrate

摘要

A Si nanocrystal based metal-oxide-semiconductor light-emitting diode (MOSLED) on Si nanopillar array is preliminarily demonstrated. Rapid self-aggregation of Ni nanodots on Si substrate covered with a thin SiO_2 buffered layer is employed as the etching mask for obtaining Si nanopillar array. Dense Ni nanodots with size and density of 30 nm and 2.8×10~10 cm~−2, respectively, can be formatted after rapid thermal annealing at 850°C for 22 s. The nano-roughened Si surface contributes to both the relaxation of total-internal reflection at device-air interface and the Fowler-Nordheim tunneling enhanced turn-on characteristics, providing the MOSLED a maximum optical power of 0.7 μW obtained at biased current of 375 μA. The optical intensity, turn-on current, maximum power slope and external quantum efficiency of the MOSLED are 140 μW/cm~2, 5 μA, 2+-0.8 mW/A and 1×10~-3, respectively, which is almost one order of magnitude larger than that of a same device made on smooth Si substrate.