Development of Light Emitting Diodes using Silicon Nanocrystals

目前，人们对硅纳米晶体的光学和电学性质有着浓厚的兴趣。特别是硅纳米晶体的强可见光发射，无论从基础物理学的角度还是从在光学器件上的潜在应用的角度，都引起了人们的广泛关注。我们使用硅和碳化硅纳米晶体制造发光二极管（LED）。红色LED的量子效率为0.1%。绿色和蓝色LED的效率非常低。液体/多孔硅结具有低的发光阈值电压和高的量子效率。为了在固态器件中获得高效率，有必要在注入材料和具有大表面的硅纳米晶体之间形成良好的接触。此外，我们还在硅纳米晶体中发现了新的非线性光学现象，如光学双稳和光限幅。利用具有可控光学特性的硅纳米晶制备的光学非线性器件是全光逻辑和计算系统的关键元件。

There is currently intense interest in optical and electronic properties silicon nanocrystals. In particular, strong visible luminescence from silicon nanocrystals has attracted much attention from the viewpoints of both fundamental physics and the potential application to optical devices. We fabricated light-emitting diodes (LEDs) using silicon and silicon carbide nanocrystals. Quantum efficiencies of red LEDs are 0.1%. The efficiencies of green and blue LEDs are very low. The liquid/porous silicon junctions have achieved the low threshold voltage for light emission and high quantum efficiencies. It is necessary to develop good contacts between the injection materials and silicon nanocrystals with large surfaces in order to obtain high efficiency in solid state devices. Moreover, we discovered new nonlinear optical phenomena in silicon nanocrystals, such as optical bistability and optical limiting. Optical nonlinear devices fabricated by silicon nanocrystals having controllable optical properties seem to be the key elements of all-optical logic and computing systems.