Browsing by Author "Hsu, Shu-Han"

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Effect of Oxygen on the Microstructural Growth and Physical Properties of Transparent Conducting Fluorine-Doped Tin Oxide Thin Films Fabricated by the Spray Pyrolysis Method
(2013)
Chantarat, N.
;
Chen, Yu-Wei
;
Hsu, Shu-Han
;
Lin, Chin-Ching
;
Chiang, Mei-Ching
We reported the fabrication of an FTO conducting thin film via a spray deposition method, which was used to investigate the effect of oxygen content in the carrier gas on deposited film morphology and properties. Using a carrier gas containing various O-2/N-2 concentrations (0%, 20%, 50%, 80%, and 100%) led to significant changes in the thickness, size, and shape of grain growth. The deposited films with 0-50% oxygen content yielded a low resistivity of similar to 10(-4) Omega-cm and a transmittance in the range of 76-96% at 550 nm. Furthermore, by changing the carrier gas concentration, the FTO films displayed different charge transport, recombination, and collection properties due to the surface and interfacial effects. These films with modified properties can be applied to dye-sensitized solar cells (DSSCs). Overall, the conversion efficiency of a solar cell based on a 0% O-2 sample was increased by approximately 2% from that of a 100% O-2 sample. The higher efficiency is mainly the result of the lower O-2 content, which minimized the grain boundaries (spacing) and improved the electron transport on the FTO film surface. (C) 2013 The Electrochemical Society. All rights reserved.
High Performance Poly Si Junctionless Transistors with Sub-5nm Conformally Doped Layers by Molecular Monolayer Doping and Microwave Incorporating CO2 Laser Annealing for 3D Stacked ICs Applications
(2015)
Lee, Yao-Jen
;
Cho, Ta-Chun
;
Sung, Po-Jung
;
Kao, Kuo-Hsing
;
Hsueh, Fu-Kuo
A junctionless (JL) fin thin film transistor (FinTFT) with a novel shell doping profile (SDP) formed by a damage-free conformal molecular monolayer doping (MLD) method and a combination of microwave annealing (MWA) and CO2 laser spike annealing (COLSA) is demonstrated and studied. MWA drives in and partially activates the MLD dopants; the resultant SDP features an ultra-shallow depth (< 5nm) and an abrupt steepness (< 0.8 nm/dec). The dopant activation of the devices experienced MLD and MWA is further enhanced by the nonmelting COLSA without dopant diffusion, and which can also avoid fin deformation and recover surface defects left by fin patterning. Thanks to the enhanced dopant activation by COLSA, the SDP-FinTFTs overall exhibit better performance than the SDP-FinTFTs without COLSA and the conventional implanted (imp) FinTFTs in terms of subthreshold swing (S.S.), on-currents (I-on by 160% compared to the SDP-FinTFTs without COLSA) and on/off current ratio (I-on/I-off > 10(7)) for 3D stacked ICs applications. Our results reveal the potential of the proposed SDP formed by MLD, MWA and COLSA enabling a JLFinTFT showing excellent performance.
Mechanism of an AZO-coated FTO film in improving the hydrogen plasma durability of transparent conducting oxide thin films for amorphous-silicon based tandem solar cells
(2012)
Chantarat, N.
;
Hsu, Shu-Han
;
Lin, Chin-Ching
;
Chiang, Mei-Ching
;
Chen, San-Yuan
An Al-doped ZnO (AZO)/F-doped SnO2 (FTO) film structure in an amorphous silicon solar cell (a-Si: H) was studied under exposure to hydrogen (H) plasma treatment via a simple spray pyrolysis. A radio-frequency magnetron sputtering method was used to deposit the FTO film first and the subsequent AZO overlayer on top of the FTO. The results of this approach suggest that the AZO film acts as a protection layer for the underlying FTO film and thus provides an excellent interface that protects the film from the direct bombardment with H+ ions and radicals. Even under exposure to H-plasma, the optical (UV-Vis) and electrical properties (Hall measurement) of the AZO/FTO double layer film show improvement in plasma stability in comparison with a single FTO film. Without the AZO overlayer, the reduction of SnO2 to metallic Sn and sub-oxidized SnO can occur in the FTO film. However, after a post-annealing treatment at 400 degrees C, the degradation of the FTO can be reversed by reoxidizing the Sn-O bonds. This interpretation of the H+ ion diffusion and the Sn-O redox process is confirmed via XPS and SIMS analysis. This investigation provides an opportunity to study the H+ ion diffusion mechanism in a metal oxide matrix in the presence of plasma and thermal effects. The study thus provides an alternative to the conventionally used FTO-based Si solar cells.
Suspended Ge Gate-All-Around Nanowire nFETs with Junction Isolation on Bulk Si
(2016)
Wan, Chia-Chen
;
Luo, Guang-Li
;
Hsu, Shu-Han
;
Hung, Kuo-Dong
;
Chu, Chun-Lin
Replacing Si channel with selective epi-Ge in mainstream bulk FinFETs can be a cost-effective solution for sub-7 nm node, but is facing severe challenges because of poor isolation to Si substrates. We demonstrate a suspended Ge gate-all-around (GAA) nanowire nFET (nNWFET) technology with junction isolation on bulk Si. Because of the low junction leakage provided by an embedded Si junction, improved electrostatics of GAA structure utilizing surrounding high-mobility {111} surfaces, and a dislocation-free channel by selectively removing the defective Ge/Si interface, a high current on/off ratio (I-ON/I-OFF of 5x10(5), which is comparable to the state-of-the-art Ge nFETs on Ge-on-insulator (GeOI), is first demonstrated using a bulk FinFET-compatible process.