Abstract
摘要:由於矽(Si)在超大型積體電路(ULSI)中的廣泛運用以及其成熟的製程技術等因素,矽一直都是製作與應用奈米結構的重要材料。雖然矽的非直接能帶(indirect bandgap)結構導致矽難以發光,利用矽奈米結構來突破非直接能帶結構的限制而製作出矽發光元件,以期能與目前功能強大的電子電路整合在同一矽晶片上,一直都是一個極為重要的研究課題。所以利用矽奈米結構來製作電子與發光元件的研究,將有助於未來在矽晶片上製作出更微小、更快速的光電整合元件的發展。因此,我們提出為期三年的研究計畫,發展利用矽奈米結構製作新穎電子與發光元件的科學與技術。本計畫主要包涵4個主要的研究項目:(1)矽奈米結構的製作與測量(2)利用矽奈米結構製作高效率發光二極體(3)利用矽奈米結構製作共振穿隧(resonant tunneling)與彈道電子傳輸(ballistic electron transport)元件(4)利用矽奈米結構製作具有光學增益(optical gain)的發光元件,並研究光子與聲子受激性放射(stimulated emissions of photons and phonons)的物理特性。
Abstract: Silicon is the dominant semiconductor material in ultra-large-scale-integration (ULSI) electronics, and so is also the desirable material for many potential applications of nanostructures. Despite the indirect bandgap, silicon nanostructures continue to be intensively investigated for the direct integration of light-emitting devices into silicon chips. The efforts in the silicon nanoelectronic and nanophotonic devices will provide the possible need for the future silicon industry. Therefore, we are proposing a three year project with four tasks intended as an investigation of the physics and technologies of novel electrical and light-emitting devices on the nanostructured silicon substrates. The four tasks in this research propose are (1) Fabrication and characterization of silicon nanostructures (2) Efficient silicon light-emitting diodes based on silicon nanostructures (3) Resonant tunneling and ballistic electron transport in silicon nanostructures (4) Optical gain and stimulated emissions of photons and phonons in silicon nanostructures.
In the first year, we will fabricated the silicon nanopillars by reactive ion etching (RIE) utilizing the self-organized nanoporous anodized aluminum as an etching mask. The silicon nanocrystals imbedded in the SiO2 layer will be fabricated using ion implantation of Si+ into a thermal oxide and subsequent post-implanted annealing. In the second year, the silicon nanocrystals imbedded in the SiO2 layer and the nanocrystalline-Si/SiO2 superlattices will be grown using reactive evaporation of silicon monoxide (SiO) powders in oxygen atmosphere. The following thermal annealing will result in the phase separation of the SiOx layers into silicon nanocrystals surrounded by SiO2. We will fabricate the efficient silicon light-emitting diodes (LED) on these nanostructured silicon substrates. The nonradaitive recombination in silicon LED will be reduced by using the floatzone growth silicon substrate, surface passivation by high-quality thermal oxides, and moderate N-type doping at the surface. The radiative recombination rate will be enhanced using silicon nanostructures. The leakage current in LED will be prevented by Si/SiO2 heterojunctions. We will use RIE together with the self-organized etching masks to texture the surface for the increase in the light-extraction efficiency. The resonant tunneling diodes will also be explored using the silicon nanocrystals imbedded in the SiO2 layer in the second year. In the third year, the ballistic electron transport in the structure of silicon nanocrystals interconnected via thin oxide films will be investigated. The optical gain in silicon nanostructures will be investigated using the variable stripe length (VSL) technique. The theoretical study has indicated that the nanostructured PN junction is necessary to enhance the optical gain coefficient in order to achieve the observation of stimulated emission in silicon. Thus the structure of a nanostructured PN junction, an
Keyword(s)
奈米結構
奈米柱狀結構
矽奈米晶體
超晶格
發光二極體
共振穿隧
彈道電子傳輸
受激性放射
nanostructure
nanopillar
silicon nanocrystal
superlattice
light-emitting diode
resonant tunneling
ballistic electron transport
stimulated emission