Browsing by Author "Chao, CW"

Now showing 1 - 10 of 10

Characterization of excimer-laser-annealed polycrystalline silicon films grown by ultrahigh-vacuum chemical vapor deposition
(2000-10-16)
Chen, YC
;
Wu, YCS
;
Tung, IC
;
Chao, CW
;
Feng, MS
Polycrystalline silicon (poly-Si) films grown by ultrahigh-vacuum chemical vapor deposition (UHVCVD) system and then annealed by excimer laser at room temperature have been investigated for the applications in polycrystalline silicon thin-film transistors (poly-Si TFTs). The results showed that the grain size of the laser-annealed poly-Si film decreased with laser energy density when a lower laser energy density below 157.7 mJ/cm(2) was used. At about the threshold laser energy density (similar to 134.5 mJ/cm(2)), the finest grain structure could be obtained due to the partial melting in the top layer of the film. When the energy density of the excimer laser was larger than the threshold energy density, the large grain growth was initiated. The largest grain structure could be obtained at similar to 184 mJ/cm(2), while its surface roughness was better than that of the nonannealed UHVCVD poly-Si films. The surface roughening was suggested to arise from the specific melt-regrowth process but not the rapid release of hydrogen or capillary wave mechanism derived from laser-annealed amorphous silicon. By use of the laser-annealed UHVCVD poly-Si films as the active layer, the fabricated poly-Si TFT exhibited a field-effect mobility of 138 cm(2)/V s, a subthreshold swing of 0.8 V/dec, a threshold voltage of 3.5 V, and an on/off current ratio of similar to 10(6). (C) 2000 American Institute of Physics. [S0003- 6951(00)03842-0].
Device characteristics of polysilicon thin-film transistors fabricated by electroless plating Ni-induced crystallization of amorphous Si
(2003-04-01)
Chao, CW
;
Wu, YCS
;
Hu, GR
;
Feng, MS
;
材料科學與工程學系
Compared with conventional solid phase crystallized (SPC) thin-film transistors (TFTs), metal-induced laterally crystallized (MILL) TFTs exhibit significantly enhanced performance. Metal films are usually deposited by the physical vapor deposition (PVD) method, which is time-consuming and expensive in terms of equipment cost. In this work, a simpler electroless plating Ni was introduced to replace PVD Ni. It was found that the morphologies and the device characteristics of Ni-induced lateral crystallization TFT were as good as those of PVD Ni-induced lateral crystallization TFT.
Effects of oxygen on the growth of Ni induced lateral crystallization of amorphous silicon films
(2003-06-26)
Lin, YD
;
Wu, YS
;
Chao, CW
;
Hu, GR
;
材料科學與工程學系
Effects of oxygen on the growth of metal (Ni) induced lateral crystallization (MILC) of amorphous silicon have been investigated. It is found that the oxygen in the annealing ambient did not degrade the MILC length or growth rate. The oxygen existence in Ni film does not degrade the MILC growth rate either. However, it retards the nucleation of poly-Si for about 4 h. This is because that NiO needed an incubation period to be reduced to nickel metal for the subsequent mediated crystallization of a-Si process. (C) 2003 Elsevier Science B.V. All rights reserved.
Electrochemically deposited Pd-induced crystallization of parallel needlelike polycrystalline silicon from prepatterned amorphous silicon thin films
(2002-02-01)
Chao, CW
;
Hu, GR
;
Wu, YS
;
Chen, YC
;
Feng, MS
Electrochemically deposited Pd-induced crystallization of prepatterned amorphous silicon (a-Si) thin films was proposed for the first time in this study. Most of palladium clusters were found to deposit on the sidewall of the amorphous-silicon islands. After samples were annealed at 530degreesC, parallel needlelike polycrystalline silicon grains were observed on the a-Si film with a constant angle of similar to55degrees from the edge. The direction of the primary grain growth was along [211] and the secondary growth occurred along [011] direction. (C) 2001 The Electrochemical Society.
Electroless plating with Pd induced crystallization of amorphous silicon thin films
(2002-11-01)
Hu, GR
;
Wu, YCS
;
Chao, CW
;
Huang, TJ
;
材料科學與工程學系
A metal-induced crystallization method can be used to decrease the crystallization temperature of amorphous silicon (a-Si). In this study, Pd metal was deposited by an electroless plating method. After it was annealed at 550degreesC, two kinds of needlelike grains were found. The direction of the primary grain was along <211> and the growth of the secondary grain occurred along the <011> direction.
Growth mechanism of laser annealing of nickel-induced lateral crystallized silicon films
(2006-01-01)
Hu, GR
;
Wu, YS
;
Chao, CW
;
Shih, HC
;
材料科學與工程學系
The growth mechanism of a hybrid process to crystallize amorphous silicon (a-Si) film was studied. In the process, a-Si was first converted to polycrystalline silicon (poly-Si) using Ni-metal-induced lateral crystallization (NILC), and then annealed with an excimer laser (ELA). Two regions based on different crystallization mechanisms were found on these NILC-ELA films: (A) a-Si melting region, and (13) a-Si/poly-Si melting region. In the a-Si melting region, the sizes and shapes of the needle Si grains were similar to those of NILC poly-Si. In the a-Si/poly-Si melting region, the shapes and sizes of poly-Si grains were quite different from those of NILC needlelike grains. Two crystallization regimes were found in the a-Si/poly-Si melting region: (1) geometrical coalescence regime and (2) complete melting regime. In the geometrical coalescence regime, the width of grains dramatically increased to 600 nm due to the geometrical coalescence of Si needle grains. However, in the complete melting regime, the NILC Si films melted completely. Small poly-Si grains were formed by homogeneous nucleation and growth.
Low temperature polycrystalline silicon thin film transistors fabricated by electroless plating Ni induced crystallization of amorphous Si
(2003)
Chao, CW
;
Wu, YCS
;
Chen, YC
;
Hu, GR
;
Feng, MS
Compared with conventional solid phase crystallized (SPC) thin-film transistors (TFTs), metal-induced laterally crystallized (MILC) TFTs exhibit significantly enhanced performance. Metal films were usually deposited by the physical vapor deposition (PVD) method. In this work, a simpler electroless plating Ni was introduced to replace PVD Ni. It was found that the morphologies and the device characteristics of Ni induced lateral crystallization TFT were as good as those of PVD Ni induced lateral crystallization TFT.
Selective growth of carbon nanotubes on prepatterned amorphous silicon thin films by electroless plating Ni
(2003-09-01)
Chao, CW
;
Wu, YCS
;
Hu, GR
;
Feng, MS
;
材料科學與工程學系
Selective growth of carbon nanotubes (CNTs) synthesized at low temperature by electroless plating Ni was proposed for the first time in this study. After electroless plating, Ni nanoparticles were selectively deposited on the prepatterned amorphous silicon (a-Si) thin films. After plasma-enhanced chemical vapor deposition, well-aligned CNTs were observed only on the Ni-coated a-Si islands. The diameter, density, and the field emission of CNTs could be controlled easily by the Ni plating time. The achievement of controlling the site density and growth area is significant for applications of carbon nanotubes as field emission devices, nanoelectrode arrays, etc. (C) 2003 The Electrochemical Society.
The effects of oxygen concentration in Ni film on the metal induced crystallization of amorphous silicon
(2003)
Lin, YD
;
Wu, YCS
;
Chao, CW
;
Hu, GR
;
材料科學與工程學系
The effects of oxygen concentration in Ni film on the metal induced crystallization of amorphous silicon were investigated. It was found that oxygen in Ni deposited film had little effect on the growth rate of polycrystalline silicon. However, an incubation period was needed for nickel oxide to be reduced to nickel metal for the subsequent mediated crystallization process.
The effects of Pd2Si on the electroless plating Pd induced crystallization of amorphous silicon thin films
(2003)
Huang, CTJ
;
Hu, GR
;
Wu, YCS
;
Chao, CW
;
材料科學與工程學系
Electroless plating Pd method has been used to induce crystallization of amorphous silicon through the formation of Pd2Si. Unfortunately, after crystallization, the Pd2Si residues in the Si film degraded the polycrystalline quality. In this study, a two-step annealing process was used to reduce the Pd2Si quantity. Besides, post-RTA treatment was used to improve the quality of poly-Si.