Browsing by Author "Chiu, Po-Chun"

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Generation of tunable blue-green light using ZnO periodically poled lithium niobate crystal fiber by self-cascaded second-order nonlinearity
(2007-08-01)
Lee, Li-Min
;
Pei, Shan-Chuang
;
Lin, Der-Fong
;
Chiu, Po-Chun
;
Tsai, Mon-Chang
Using a novel self-cascaded first-order second-harmonic generation (SHG) and third-order sum-frequency generation (SFG) in a ZnO periodically poled lithium niobate crystal fiber, tunable blue-green light was demonstrated. At a domain pitch of 15.45 mu m, the SHG signal and its fundamental signal at 1423.9 nm can satisfy the third-order SFG quasi-phase-matched (QPM) condition. The measured SHG power at 714.2 nm was 12.25 mW under 100 mW input power, and the estimated nonlinear coefficient (d(33)) achieved was 25.3 pm/V. The self-cascaded SHG+SFG power measured at 477.1 nm was similar to 700 mu W under 350 mW input power. The maximum internal efficiency of the SHG is 14.84%. The tuning range of the self-cascaded SHG and SFG generated tunable blue-green light was more than 40 nm, from 471.3 to 515 nm. The maximum simulated 3 dB bandwidth achieved using a gradient-period QPM structure is 196 nm, which is from 1476 to 1672 nm. The gain-bandwidth product of the self-cascaded SHG and SFG processes decreases drastically as the bandwidth is broadened. (c) 2007 Optical Society of America.
pH Sensing Characteristics of Extended-Gate Field-Effect Transistor Based on Al-Doped ZnO Nanostructures Hydrothermally Synthesized at Low Temperatures
(2011-11-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Chiu, Po-Chun
;
Chou, Jung-Chuan
;
Chen, Cheng-Wei
The pH sensing properties of an extended-gate field-effect transistor (EGFET) with Al-doped ZnO (AZO) nanostructures are investigated. The AZO nanostructures with different Al dosages were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85 degrees C. The pH sensing characteristics of pH-EGFET sensors with an Al dosage of 1.98 at% can exhibit a higher voltage sensitivity of 57.95 mV/pH, a larger linearity of 0.9998, and a wide sensing range of pH 1-13, attributed to the well-aligned nanowire (NW) array, superior crystallinity, less structural defects, and better conductivity. Consequently, the hydrothermally grown AZO NWs demonstrate superior pH sensing characteristics and reveal the potentials for flexible and disposable biosensors.
Reliability improvement of InGaZnO thin film transistors encapsulated under nitrogen ambient
(2012-04-09)
Wu, Chun-Yu
;
Cheng, Huang-Chung
;
Wang, Chao-Lung
;
Liao, Ta-Chuan
;
Chiu, Po-Chun
The nitrogen ambient encapsulation (NAE) technique is introduced to improve the reliability issue for the amorphous InGaZnO (a-IGZO) thin-film transistors under positive gate bias stress (PGBS). For the NAE devices, the threshold voltage (Vth) shift is significantly decreased from 1.88 to 0.09 V and the reduction of saturation drain current is improved from 15.75 to 5.61 mu A as compared to the bare a-IGZO counterparts after PGBS. These improvements are attributed to the suppression of negatively charged oxygen adsorption on the a-IGZO backsurface and thereby well maintain the channel potential of NAE devices, which in turn sustain the Vth during PGBS. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3702794]