Ching-Hung Chen

Electrical and Reliability Characteristics of High-

In this letter, we investigated the electrical and reliability characteristics of high- κ HoTiO₃ amorphous indium-gallium-zinc oxide ( α-IGZO) thin-film transistor (TFT) devices. The α-IGZO TFT device incorporating an HoTiO₃ dielectric exhibited excellent electrical characteristics in terms of a low threshold voltage of 0.12 V, a high field-effect mobility of 21.4 cm²/V_s, a small subthreshold swing of 160 mV/decade, and a high I_ON/I_OFF current ratio of 1.3 ×10⁸. These results are attributed to the incorporation of TiO_x into the Ho₂O₃ film forming the smooth surface roughness and thus reducing the oxygen vacancies. Furthermore, the threshold voltage stability of HoTiO₃ α-IGZO TFT was studied under both positive and negative bias stress conditions.

\kappa~{\rm HoTiO}_{3}~\alpha

Investigated transfer characteristics on threshold voltage instability behavior in amorphous indium-gallium-zinc oxide thin-film transistor (α-IGZO TFT). A two-step electrical degradation behavior of α-IGZO TFT was found under gate-bias stress. A usual small positive shift followed by a special negative shift of threshold voltage is characterized in the α-IGZO TFT device. We suggest that the positive shift of the threshold voltage is due to the charge trapping in the gate dielectric and/or at the channel/dielectric interface, while the negative shift of threshold voltage is assigned to electric field-induced extra electron carriers from H2O molecules in the back channel protective layer. We conclude that the H2O molecules and the quality of passivation layer affect the degradation behavior of α-IGZO TFT devices.

-InGaZnO Thin-Film Transistors

In this paper, we compared the structural and electrical properties of high- κ Gd₂O₃ and GdTiO₃ gate dielectrics for an amorphous indium-gallium-zinc oxide ( α-IGZO) thin-film transistor (TFT) application. In comparison with the Gd₂O₃ dielectric, the α-IGZO TFT featuring the GdTiO₃ dielectric exhibited better electrical characteristics in terms of a large field effect mobility of 26.9 cm²/Vs, a low threshold voltage of 0.04 V, a high ION/IOFF ratio of 1.2×10⁸, and a low subthreshold swing of 200 mV/decade. We attribute these results to the incorporation of Ti into the Gd₂O₃ film, forming a smooth surface and thus reducing density of interface states at the oxide/channel interface. In addition, the stability of threshold voltage on high- κ Gd₂O₃ and GdTiO₃ a-IGZO TFTs was studied under positive gate bias stress.

Two-step Electrical Degradation Behavior in α-InGaZnO Thin-film Transistor Under Gate-bias Stress

In this study, we report the structural and electrical characteristics of high-κ Sm2O3 and SmTiO3 charge trapping layers on an indium–gallium–zinc oxide (IGZO) thin-film transistor (TFT) for non-volatile memory device applications. The IGZO TFT non-volatile memory featuring a SmTiO3 charge trapping layer exhibited better characteristics, including a larger memory window (2.7 V), long charge retention time (105 s with charge loss <15%) and better endurance performance for program/erase cycles (104), compared with a Sm2O3 charge trapping layer. These results can be attributed to the SmTiO3 film possessing a high dielectric constant and deep trapping level. The high-κ SmTiO3 is an excellent candidate for use as the trapping layer in IGZO TFT non-volatile memories.

Comparison of High-

In this study, we developed high-κ Ho2O3 and HoTixOy gate dielectrics for amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistor (TFT) applications. X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy were used to study the structural, morphological and chemical features of Ho2O3 and HoTixOy dielectric films. Compared with the Ho2O3 dielectric, the a-IGZO TFT incorporating the high-κ HoTixOy gate dielectric exhibited very good electrical characteristics, such as a high Ion/off ratio of 1.1 × 108, a high field effect mobility of 20.6 cm2 V−1 s−1, a low threshold voltage of 0.23 V, and a low subthreshold swing of 183 mV decade−1. These results are probably due to the incorporation of Ti into the Ho2O3 film, resulting in the formation of a smooth surface and a low density of interface states at the oxide/channel interface. In addition, the stability of high-κ Ho2O3 and HoTixOy a-IGZO TFTs was investigated under positive gate-bias stress (PGBS) and negative gate-bias stress (NGBS). The electron charge trapping at the dielectric–channel interface resulted from the PGBS, whereas the oxygen vacancies occurred in the a-IGZO under the NGBS.

\kappa~{\rm Gd}_{2}{\rm O}_{3}

We compared the structural properties and electrical characteristics of high-κ Lu2O3 and Lu2TiO5 gate dielectrics for amorphous indium-gallium-zinc oxide (α-InGaZnO) thin-film transistor (TFT) applications. The Lu2O3 film has a strong Lu2O3 (400) peak in the X-ray diffraction pattern, while the Lu2TiO5 sample shows a relatively weak Lu2TiO5 (102) peak. Atomic force microscopy reveals that the Lu2O3 dielectric exhibits a rougher surface (about three times) than Lu2TiO5 one. In X-ray photoelectron spectroscopy analysis, we found that the intensity of the O 1s peak corresponding to Lu(OH)x for Lu2O3 film was higher than that of Lu2TiO5 film. Furthermore, compared with the Lu2O3 dielectric, the α-InGaZnO TFT using the Lu2TiO5 gate dielectric exhibited a lower threshold voltage (from 0.43 to 0.25u2009V), a higher Ion/Ioff current ratio (from 3.5u2009×u2009106 to 1.3u2009×u2009108), a smaller subthreshold swing (from 276 to 130u2009mV/decade), and a larger field-effect mobility (from 14.5 to 24.4u2009cm2/V s). These results are probably d...

and

In this study, we developed an amorphous indium-gallium-zinc oxide (α-IGZO) thinfilm transistor (TFT) incorporating high-κ Sm₂TiO₅ gate dielectrics. The high-κ Sm₂TiO₅ α-IGZO TFT after annealing at 400°C exhibited very good electrical characteristics, such as a high I_on/off ratio of 5.27×10⁷, a high field-effect mobility of 27.8 cm²/V-sec, a low threshold voltage of 0.2 V, and a low subthreshold swing of 136 mV/decade. These results are probably due to the incorporation of Ti into the Sm₂O₃ film, resulting in the formation of good Sm₂TiO₅ gate dielectric and low density of interface states at the oxide/channel interface.

{\rm GdTiO}_{3}~\alpha

This paper describes the effect of titanium content on the structural and electrical properties of ErTixOy charge storage layers in amorphous indium-gallium-zinc oxide (α-IGZO) thin-film transistor (TFT) nonvolatile memory (NVM) devices. X-ray diffraction, Auger electron spectroscopy, and X-ray photoelectron spectroscopy were used to study the film structural, depth profiling, and chemical features, respectively, of these films as the functions of the growth conditions (Ti plasma powers of 60, 100, and 140 W). The ErTixOy IGZO TFT NVM devices fabricated at the 100-W condition exhibited a larger memory window of 4.1 V, a smaller charge loss of 13% (after ten years), and a better endurance characteristic (up to 105 program/erase cycles), as compared with other conditions. This result suggests that the Er2TiO5 film featuring a high dielectric constant and reducing an Er(OH)x layer can provide the higher charge-trapping efficiency and deeper electron trapping levels.

-InGaZnO Thin-Film Transistors

In this letter, we investigate the structural and electrical characteristics of Er₂O₃ and ErTixOy charge-trapping layers for InGaZnO thin-film transistor (TFT) nonvolatile memory devices for the first time. Compared with the Er₂O₃ layer, the InGaZnO TFT memory device incorporating the ErTixOy charge-trapping layer exhibited a lower subthreshold swing of 146 mV/decade, a larger memory window of 3.9 V, a smaller charge loss of 10%, and better endurance performance for program/erase cycle up to 10⁵, presumably due to the high charge efficiency in the ErTi_xO_y film.

Electrical characteristics of gallium–indium–zinc oxide thin-film transistor non-volatile memory with Sm2O3 and SmTiO3 charge trapping layers

We investigated the structural properties and electrical characteristics of GdTiO₃ dielectrics for IGZO TFT devices. We used XRD, XPS, and AFM to examine the structural, compositional, and morphological features of the GdTiO₃ film, respectively. The IGZO TFT featuring a GdTiO₃ gate dielectric exhibited a large field-effect mobility of 32.3 cm²/V-s, a small threshold voltage of 0.14 V, a high Ion/Ioff current ratio of 4.2 × 10⁸, and a low subthreshold swing of 213 mV/decade.