Browsing by Author "Chang, Chih-Hsiang"

Now showing 1 - 15 of 15

Effects of Backchannel Passivation on Electrical Behavior of Hetero-Stacked a-IWO/IGZO Thin Film Transistors
(2018-01-01)
Liu, Po-Tsun
;
Chang, Chih-Hsiang
;
Kuo, Po-Yi
;
Chen, Po-Wen
;
光電工程學系
This study investigates the effects of positive gate-bias stress (PGBS) on the electrical instability of amorphous InWO/InGaZnO (a-IWO/IGZO) stacked thin-film transistors (TFTs) with a backchannel passivation layer of SiO2 or Al2O3 film. After the application of PGBS to a-IWO/IGZO TFTs with an SiO2 passivation layer, abnormal negative threshold voltage (Vth) shifts were observed, while positive Vth shifts were observed in the TFTs with an Al2O3 passivation layer. This unusual positive bias instability is explained using a two-step electrical degradation behavior model, including both electron trapping and moisture absorption at the damaged back channel interface between a-IWO/IGZO TFTs and the SiO2 passivation layer. (C) 2018 The Electrochemical Society.
Effects of Ga2O3 deposition power on electrical properties of cosputtered In-Ga-Zn-O semiconductor films and thin-film transistors
(2014-05-01)
Lee, Yih-Shing
;
Chang, Chih-Hsiang
;
Lin, Yuan-Che
;
Lyu, Rong-Jhe
;
Lin, Horng-Chih
In this study, we have successfully fabricated In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) with various Ga2O3 deposition powers prepared using a two radio-frequency (RF) (ceramics targets: In2O3 and Ga2O3) and one direct-current (DC) (metallic target: Zn) magnetron cosputtering system at room temperature. The carrier concentration for the IGZO films decreases to less than 3 x 10(16) cm(-3) when the Ga2O3 deposition power is 175W and Hall mobility decreases from 12.8cm(2)V(-1) s(-1) and saturates at 4.6 cm(2)V(-1) s(-1) with increasing Ga2O3 deposition power. The increase in the resistivity of the cosputtered films correlates with the decrease in the crystallinity of the InGaZn7O10 phase and the phase transformation from InGaZn7O10 to InGaZn2O5 with increasing Ga2O3 deposition power. With an optimum Ga2O3 deposition power of 150W, cosputtered IGZO TFTs with a higher, saturated drain current of 4.5 mu A, good saturation mobility, mu(sat) of 4.92cm(2)V(-1) s(-1), I-on/I-off of 10(9), a low subthreshold swing (SS) of 0.27V/decade, and R-SD of 30 k Omega have been successfully fabricated. (C) 2014 The Japan Society of Applied Physics
Effects of Nitrogen on Amorphous Nitrogenated InGaZnO (a-IGZO:N) Thin Film Transistors
(2016-10)
Liu, Po-Tsun
;
Chang, Chih-Hsiang
;
Fuh, Chur-Shyang
;
Liao, Yu-Tei
;
Sze, Simon M.
In this study, the role of nitrogen in the dc-sputtered amorphous indium gallium zinc oxide (a-IGZO):N are explored extensively with a series of nitrogen gas flow rates during IGZO film deposition. The amorphous film structure and the evolution of chemical bondings were confirmed by X-ray diffractometer and X-ray photoelectron spectroscopy spectra analysis. Also, electrical performance and reliability of a-IGZO: N thin-film transistors (TFTs) formed with different nitrogen gas flow rates were analyzed to study the effects of nitrogen on TFT devices. The device performance of a-IGZO: N TFTs can be enhanced with a proper nitrogen doping concentration. However, with excess nitrogen incorporation in the a-IGZO: N channel layer, both electric characteristic and reliability are degraded due to the extra creation of oxygen deficiencies in a-IGZO: N film and easy formation of unstable interface between gate insulator and channel layer, which were confirmed by low-frequency noise measurement. This potential issue of a-IGZO: N TFT characteristics can be effectively released by introducing a post-treatment on the surface of gate dielectric layer. The optimized electrical characteristics of a-IGZO: N TFT can exhibit a carrier mobility of 19.21 cm(2)/V . s, subthreshold swing of 0.26 V/decade and threshold voltage (V-th) of -0.74 V in this study.
Electrical performance and photo-responses enhancement by in situ nitrogen incorporation to amorphous InGaZnO thin-film transistors
(2011)
Teng, Li-Feng
;
Liu, Po-Tsun
;
Fuh, Chur-Shyang
;
Chou, Yi-Teh
;
Li, Fu-Hai
We studied wavelength dependent photo-responses in amorphous nitrogenated InGaZnO thin-film transistors (a-IGZO:N TFTs). The a-IGZO:N active layer was deposited by dc reactive sputter with a nitrogen and argon gas mixture at room temperature and performed the superior characteristics while comparing with the intrinsic IGZO TFTs.
Enhancement of reliability and stability for transparent amorphous indium-zinc-tin-oxide thin film transistors
(2016-01-01)
Liu, Po-Tsun
;
Chang, Chih-Hsiang
;
Fuh, Chur-Shyang
;
電子工程學系及電子研究所
;
光電工程學系
We studied the influence of the backchannel passivation layer (BPL) on the ambient stability of amorphous indium-zinc-tin-oxide thin-film transistors (a-IZTO TFTs), in which atomic layer deposited (ALD) Al2O3 films and plasma-enhanced chemical vapor deposited (PECVD) SiO2 films were separately used to be the channel passivation layers. It was observed that the BPL deposition process strongly affects device performance and stability. From the results of the extracted activation energy (Eact), the Al2O3 passivation layer can reduce the trap density in localized tail states, which improves the mobility of a-IZTO TFTs. Compared with the SiO2 passivation layer, the Al2O3 passivation process effectively suppresses H injection into the a-IZTO channel layer underneath with secondary ion mass spectrometer analysis. In addition, it is found that the a-IZTO TFT with the Al2O3 passivation layer can enhance resistance against negative bias illumination stress (NBIS), making it reliable for realistic operation in flat panel displays.
Evaluation of TiN/Cu Gate Metal Scheme for AlGaN/GaN High-Electron-Mobility Transistor Application
(2013-09-01)
Lin, Yueh-Chin
;
Chang, Chih-Hsiang
;
Li, Fang-Ming
;
Hsu, Li-Han
;
Chang, Edward Yi
The TiN/Cu metal scheme as gate metal for AlGaN/GaN high-electron-mobility transistors (HEMTs) is investigated. The copper-gated devices show comparable DC characteristics to the conventional Ni/Au-gated devices. No obvious of changes in I-DS and I-GS were observed for the device after being stressed at V-DS = 200 and V-GS = -5 V for 32 h. The thermal stability test indicates comparable Schottky barrier height for the TiN/Cu gate metal on GaN before and after 250 degrees C annealing for 1 h. Overall, the AlGaN/GaN HEMT with the TiN/Cu gate metal structure demonstrates excellent device DC characteristics, good thermal stability, and stable performance after a high-voltage stress test. (c) 2013 The Japan Society of Applied Physics
Flexible Non-Volatile Memory Based on Indium-Gallium-Zinc-Oxide with Excellent Reliability and Flexibility
(2012)
Fan, Yang-Shun
;
Hsu, Ching-Hui
;
Chang, Chih-Hsiang
;
Huang, Wei-Hsun
;
Yu, Ming-Chang
The memory characteristics of a-IGZO RRAM reveal excellent reliability including 1000 times DC sweep endurance, 10(4) pulse endurance, 10(4)s data retention with read disturb immunity. Furthermore, this work also demonstrated on flexible substrate, which shows the very potential flexibility applications.
Fracture of cobalt chrome, fully-coat beaded femoral revision long stem, a clinical outcomes study
(2018-02-01)
Chang, Chih-Hsiang
;
Lin, Po-Chun
;
Shih, Cheng-Min
;
Chen, Chun-Chieh
;
Hsieh, Pang-Hsin
Background: Femoral bone loss during revision total hip arthroplasty poses a challenging problem. Bypass fixation over the diaphysis has achieved clinical success in cases of proximal femoral bone loss. Fracture of cementless, fully bead-coated femoral stem is an uncommon complication. The purpose of this study is to analyze the patients with and without fracture stem and find out the possible risk factors. Methods: From 2006 to 2012, a total of 251 revision long stems (Zimmer, Warsaw, IN) were implanted. In the same period, 17 broken stems that underwent treatment were included for analysis. Patients' demographic data, pattern of femoral bone loss, stem size, medial calcar support in the proximal region of the stem, and the timing of stem breakage were collected and analyzed. Results: The stem size in patients with a broken stem was smaller (p < 0.001), and medial calcar defect was 12.4% and 100% (p < 0.001), respectively. The bone defect was greater in broken group (p = 0.024). The mean duration between revision surgery and stem breakage was 58.07 +/- 36.98 months. Smaller stem size, greater bone defect, and inadequate medial calcar bone support were major risk factors for stem breakage. Conclusions: Bypass fixation in the distal diaphysis with a long stem prosthesis without adequate bone support over medial calcar area may cause stress concentration in the long stem and a fatigue fracture. Use of a smaller prosthesis is the major risk of stem broken. It is essential to repair the proximal femoral bone deficiency and implant selection for better metaphyseal engagement to prevent further stem complications.
Investigation on Effects of Composition on Transparent Aluminum Zinc Tin Oxide Thin-Film Transistors
(2012-01-01)
Fuh, Chur-Shyang
;
Teng, Li-Feng
;
Fan, Yang-Shun
;
Chang, Chih-Hsiang
;
Liu, Po-Tsun
We investigated on electrical performance of amorphous Al-Zn-Sn-O thin film transistor (AZTO TFT). The mobility enhanced while the concentration of Sn increased. The improved stability can be attributed to the increase of Sn concentration and enhancement of bonding energy of metal ion with the increase of O-2 gas flow rate.
Investigation on plasma treatment for transparent Al-Zn-Sn-O thin film transistor application
(2013-12-31)
Chang, Chih-Hsiang
;
Liu, Po-Tsun
;
光電工程學系
;
顯示科技研究所
;
Department of Photonics
This work reported the physical characteristics and electrical performance of amorphous Al-Zn-Sn-O thin film transistor (a-AZTO TFT) device under the temperature effects of thermal annealing process and various gas plasma post-treatments. The thermal annealing at 450 degrees C could strengthen the oxygen bonding of a-AZTO film, thereby improving the film quality and TFT device performance. In addition, the oxygen deficient can be reduced effectively by the O-2 and N2O plasma treatments, respectively, leading to enhanced electrical reliability. Also, the optical energy gap of a-AZTO films with O-2 or N2O plasma treatment was measured about 3.5 eV, which indicated that all of the a-AZTO films were insensitive to visible light. On the other hand, the electron mobility of a-AZTO TFT was observed to be promoted after NH3 plasma post-treatment. The improvement could be attributed to a slight doping effect of H+ ions. These results showed the potential of post-treatments for flat panel displays applications of transparent a-AZTO TFT technology. (C) 2013 Elsevier B. V. All rights reserved.
Performance and Reliability of Non-linear Al-Zn-Sn-O based Resistive Random Access Memory
(2015)
Fan, Yang-Shun
;
Chan, Wei-Liang
;
Chang, Chih-Hsiang
;
Zheng, Guang-Ting
;
Chang, Che-Chia
The Al-doped zinc tin oxide based RRAM with nonlinearity characteristic was demonstrated. The inhabit ratio (I.R.) of 34 was achieved by inserting similar to 2nm Al2O3 tunnel barrier to ensure the possible incorporation of RRAM cell into high density cross-type array structure. Furthermore, the reliability with endurance and retention are also examined.
Reduced parasitic contact resistance and highly stable operation in a-In-Ga-Zn-O thin-film transistors with microwave treatment
(2016-11-30)
Liu, Po-Tsun
;
Chang, Chih-Hsiang
;
Zheng, Guang-Ting
;
Fuh, Chur-Shyang
;
Teng, Li-Feng
In this work, we studied the effects of microwave annealing process on amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) and demonstrated a high performance and reliable device characteristics. The characteristic trapping time (tau) derived from stretched-exponential model was extracted to exhibit the quality improvement of a-IGZO thin film. The microwave annealing features a selective heating and potentially avoids the damage to materials neighboring the a-IGZO channel layer in TFT device structure during thermal processes, resulting in lower parasitic source to drain resistance. (C) 2016 Elsevier B.V. All rights reserved.
Stability study of indium tungsten oxide thin-film transistors annealed under various ambient conditions
(2017-02-01)
Qu, Mingyue
;
Chang, Chih-Hsiang
;
Meng, Ting
;
Zhang, Qun
;
Liu, Po-Tsun
Amorphous tungsten-doped indium oxide thin-film transistors (a-IWO-TFTs) are prepared by RF sputtering and annealed in air, O-2, and N-2 ambients. The influence of annealing ambient on the electrical characteristics and stability of the a-IWO-TFTs is investigated. It is found that the characteristics and stability are improved in O-2 and N-2 ambients, which can be explained by the reduction of structural defects and oxygen vacancies. When annealed in O-2, the TFT device with saturation mobility of 27.55cm(2)V(-1)s(-1), threshold voltage of 0.5V and drain current on-off ratio of 10(8) is obtained. After an applied V-GS of 25 and -25V for 2000s in darkness, the values of Delta V-th are 4.5 and -0.92V, respectively.
Study on Transparent Amorphous Indium Oxide Thin Film Transistors Technology
(2015)
Chang, Chih-Hsiang
;
Lai, Yu-Chia
;
Fan, Yang-Shun
;
Chang, Che-Chia
;
Liu, Po-Tsun
In this study, we analyzed the In2O3 thin flints with different oxygen How rate during sputtering as the transistor\'s channel layer. The electrical analysis including device\'s reliability and material analysis were both examined.
Suppression of photo-bias induced instability for amorphous indium tungsten oxide thin film transistors with bi-layer structure
(2016-06-27)
Liu, Po-Tsun
;
Chang, Chih-Hsiang
;
Chang, Chih-Jui
;
光電工程學系
;
Department of Photonics
This study investigates the instability induced by bias temperature illumination stress (NBTIS) for an amorphous indium-tungsten-oxide thin film transistor (a-IWO TFT) with SiO2 backchannel passivation layer (BPL). It is found that this electrical degradation phenomenon can be attributed to the generation of defect states during the BPL process, which deteriorates the photo-bias stability of a-IWO TFTs. A method proposed by adding an oxygen-rich a-IWO thin film upon the a-IWO active channel layer could effectively suppress the plasma damage to channel layer during BPL deposition process. The bi-layer a-IWO TFT structure with an oxygen-rich back channel exhibits superior electrical reliability of device under NBTIS. Published by AIP Publishing.