Porous silicon nanocomposites for optoelectronic and telecommunication applications.

摘要

Porous silicon is composed of a highly interconnected matrix of nanometer size silicon crystals. The nanostructured material has been widely studied as a result of its efficient visible luminescence, large surface area, ability to control and manipulate light, and compatibility with standard silicon microelectronics. This work takes advantage of the large surface area porous silicon possesses in order to introduce and manipulate the visible and infrared optical properties of polymer and erbium doped porous silicon nanocomposites, respectively. The ability to efficiently emit light from silicon-based materials impacts a variety of optoelectronic and telecommunication applications. Porous silicon-polymer nanocomposites have been fabricated and depending on the dielectric constant of the infiltrated polymers, the photoluminescence can be tuned to emit in different regions of the visible spectrum. Excitonic screening due to the presence of the polymers causes the emission to blue shift as much as 222 meV. Erbium-doped porous silicon one-dimensional and two-dimensional photonic crystals are also fabricated and characterized. The erbium emission is tuned to appear in different spectral regions, narrowed to a full width at half maximum of 12 nm, directed to a 20° emission cone, and enhanced by a factor of 38 times when incorporated in one-dimensional photonic structures. Two-dimensional photonic structures consisting of periodic arrays of air holes electrochemically etched into crystalline silicon have been produced. Structures 150 μm deep with aspect ratios greater than 50:1 are constructed and shown to support erbium emission. Light emitting devices from erbium-doped porous silicon nanocomposites have been fabricated and exhibit stable room-temperature electroluminescence under both forward and reverse bias conditions. The devices demonstrate an exponential electroluminescence dependence with external quantum efficiencies of 0.01%. The ability to control and manipulate light from silicon based materials opens the door to a new era of technology, in which optical silicon circuits can generate, transmit, and process information for optical computing applications.