Browsing by Author "Li, Jinchai"

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Effect of the surface-plasmon-exciton coupling and charge transfer process on the photoluminescence of metal-semiconductor nanostructures
(2013)
Yin, Jun
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Yue, Chuang
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Zang, Yashu
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Chiu, Ching-Hsueh
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Li, Jinchai
The effect of direct metal coating on the photoluminescence (PL) properties of ZnO nanorods (NRs) has been investigated in detail in this work. The direct coating of Ag nanoparticles (NPs) induces remarkable enhancement of the surface exciton (SX) emissions from the ZnO NRs. Meanwhile, the charge transfer process between ZnO and Ag also leads to notable increment of blue and violet emissions from Zn interstitial defects. A thin SiO2 blocking layer inserted between the ZnO and Ag has been demonstrated to be able to efficiently suppress the defect emission enhancement caused by the direct contact of metal-semiconductor, without weakening the surface-plasmon-exciton coupling effect. A theoretical model considering the type of contacts formed between metals, ZnO and blocking layer is proposed to interpret the change of the PL spectra.
High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability
(2014-06-05)
Yang, Weihuang
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Li, Jinchai
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Zhang, Yong
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Huang, Po-Kai
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Lu, Tien-Chang
High internal efficiency and high temperature stability ultraviolet (UV) light-emitting diodes (LEDs) at 308 nm were achieved using high density (2.5 x 10(9) cm(-2)) GaN/AlN quantum dots (QDs) grown by MOVPE. Photoluminescence shows the characteristic behaviors of QDs: nearly constant linewidth and emission energy, and linear dependence of the intensity with varying excitation power. More significantly, the radiative recombination was found to dominant from 15 to 300 K, with a high internal quantum efficiency of 62% even at room temperature.
Interface Engineering for High-Performance Top-Gated MoS2 Field-Effect Transistors
(2014-09-24)
Zou, Xuming
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Wang, Jingli
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Chiu, Chung-Hua
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Wu, Yun
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Xiao, Xiangheng
Experimental evidence of the optimized interface engineering effects in MoS2 transistors is demonstrated. The MoS2/Y2O3/HfO2 stack offers excellent interface control. Results show that HfO2 layer can be scaled down to 9 nm, yet achieving a near-ideal sub-threshold slope (65 mv/dec) and the highest saturation current (526 mu A/mu m) of any MoS2 transistor reported to date.
Rational Design of ZnO:H/ZnO Bilayer Structure for High Performance Thin-Film Transistors
(2016-03-30)
Abliz, Ablat
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Huang, Chun-Wei
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Wang, Jingli
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Xu, Lei
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Liao, Lei
The intriguing properties of zinc oxide-based semiconductors are being extensively studied as they are attractive alternatives to current silicon-based semiconductors for applications in transparent and flexible electronics. Although they have promising properties, significant improvements on performance and electrical reliability of ZnO-based thin film transistors (TFTs) should be achieved before they can be applied widely in practical applications. This work demonstrates a rational and elegant design of TFT, composed of poly crystalline ZnO:H/ZnO bilayer structure without using other metal elements for doping. The field-effect mobility and gate bias stability of the bilayer structured devices have been improved. In this device structure, the hydrogenated ultrathin ZnO:H active layer (similar to 3 nm) could provide suitable carrier concentration and decrease the interface trap density, while thick pure-ZnO layer could control channel conductance. Based on this novel structure, a high field-effect mobility of 42.6 cm(2) V-1 s(-1), a high on/off current ratio of 108 and a small subthreshold swing of 0.13 V dec(-1) have been achieved. Additionally, the bias stress stability of the bilayer structured devices is enhanced compared to the simple single channel layer ZnO device. These results suggest that the bilayer ZnO:H/ZnO TFTs have a great potential for low-cost thin-film electronics.
The different roles of contact materials between oxidation interlayer and doping effect for high performance ZnO thin film transistors
(2015-02-02)
Xu, Lei
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Huang, Chun-Wei
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Abliz, Ablat
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Hua, Yang
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Liao, Lei
To improve the performance of ZnO thin film transistors (TFTs) by using appropriate metal contacts, the different roles of contact materials between oxidation interlayer and doping effect are investigated. With careful characterization, an oxidation interlayer has been verified at the interface between ZnO film and Al or Ti contact, which is suggested to be responsible for contact resistance and thermal reliability. On the other hand, it is observed that the doping effect is the main reason for the Sn or Cu contact characteristics. The superior contact using Sn is due to an oxidation-free interface, donor doping effect, and a low barrier height. By using a metal contact with a high Gibbs free energy, the metal layer would hardly consume oxygen from channel layer during sputtering and easily form no oxidation interlayer. Thus, choosing a metal contact is important when fabricating high-performance metal-oxide TFTs for flat-panel displays. (C) 2015 AIP Publishing LLC.