Fabrication and Applicaion of Silicon Nano-structures

• Main Authors: Zhao-Ren Huang, 黃昭仁
• Other Authors: Ching-Fuh Lin
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/52591858114937034016

碩士 === 國立臺灣大學 === 光電工程學研究所 === 93 === Technology of nano-structures on silicon is investigated. An excimer laser pulse melts a thin surface layer of silicon through a quartz mold, and it is embossed into the resulting liquid layer. There are two methods for quartz mold fabrication. First, etch the surface of quartz to form nano-pillars using nano-grains of gold as dry etching mask. The pattern and size of gold nano-grains can be controlled by different thermal treatment conditions. The resulting quartz nano-pillars are as small as 20 nm in diameter, 20~30 nm in height, and the gaps among them are about 20 nm. Second, E-beam lithography is used to fabricate quartz molds. Multi-layer structures of resist/electro-conductive materials/quartz are proposed to narrow down the linewidth and pitch of designed patterns. Nano-structures are successfully imprinted on silicon with fabricated quartz molds. The result of laser-assisted imprint is attributed to the low viscosity of molten silicon and the characteristic of volume expansion when silicon transforms from liquid to solid. Finally, thermal diffusion is used to fabricate nano-structured silicon pn junction LEDs, the external quantum efficiency of EL of which is up to 6x10-5 at room temperature. Phonon-assisted and exciton-involved radiative recombination dominates the EL spectra, the main peak of which corresponds to the bandgap of silicon. In addition, the fabrication of dry etching or thermal diffusion is high damage process to silicon crystal quality known by measuring minority carrier lifetime from bulk silicon, while laser-assisted imprint is low damage one. Based on the reason, laser-assisted imprint and diffusion are proposed to fabricate nano-structured silicon pn junction LEDs for the breakthrough of light from silicon.