Browsing by Author "Shieh, J"

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Emission of bright blue light from mesoporous silica with dense Si (Ge) nanocrystals
(2005)
Cho, AT
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Shieh, JM
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Shieh, J
;
Lai, YF
;
Dai, BT
Three-dimensional Si (Ge) nanocrystals (NCs) were dispersed within the nanopores of mesoporous silica films by high-density plasma (HDP), low-density plasma, or implantation. Surface states of the resulting Si (Ge) NCs/silica arrays initiate blue-white photoluminescence (PL). HDP makes reactive species highly mobile and enables deposited NCs bonded with pore-wall well, therefore, efficiently constructing photoemission arrays. The mean density of HDP-synthesized semiconducting NCs is as high as 1 x 10(18)/cm(3). Accordingly, blue PL of arrays obtained with HDP, which is 4- 7 times stronger than those obtained with other methods, exhibits quantum-efficiency of 1%, near the reported value for green-to-red light emission from quantum-confined Si NCs. © 2005 The Electrochemical Society. All rights reserved.
Low-temperature growth of polycrystalline ge films on SiO2 substrate by HDPCVD
(2005)
Yang, MJ
;
Shieh, J
;
Hsu, SL
;
Huang, IJ
;
Leu, CC
Pure and high-quality polycrystalline Ge films have been deposited directly onto fully SiO2 covered substrates by high-density plasma chemical vapor deposition (HDPCVD) system. Only a tiny amount of O and C near the surface has been observed from X-ray photoelectron spectroscopy and Auger electron spectroscopy data, which may come from surface oxidation and contamination. Very pure Ge composition has been achieved in the bulk of the films. The cubic structure with primarily (111), (220), and (311) orientations of the Ge films is mainly composed of fine grains and can be unambiguously identified from X-ray diffraction patterns. Furthermore, successful Ge film depositions with nearly no incubation time are demonstrated using a mixture of GeH4/H-2 as process gas at 400 degrees C. Thickness vs. time analysis was performed by high-resolution transmission electron microscopy. The HDPCVD technique used was able to provide a simple, powerful, and reliable approach in the fabrication of polycrystalline Ge thin film transistors. (C) 2005 The Electrochemical Society.