Browsing by Author "Jhu, Jhe-Ciou"

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Abnormal Subthreshold Leakage Current at High Temperature in InGaZnO Thin-Film Transistors
(2012-04-01)
Chang, Geng-Wei
;
Chang, Ting-Chang
;
Jhu, Jhe-Ciou
;
Tsai, Tsung-Ming
;
Syu, Yong-En
Abnormal subthreshold leakage current is observed at high temperature in amorphous InGaZnO thin-film transistors. The transfer curve exhibits an apparent subthreshold current stretch-out phenomenon that becomes more serious with increasing temperatures. The negative bias temperature instability experiment has been used to prove high-temperature-induced hole generation. Furthermore, the transfer characteristics with different drain voltages have been also used to confirm the status of hole accumulation. These pieces of evidence clearly defined the stretch-out phenomenon, which is caused by thermal-induced hole generation and accumulation at the source region that leads to source-side barrier lowering.
Investigation of Hydration Reaction-Induced Protons Transport in Etching-Stop a-InGaZnO Thin-Film Transistors
(2015-10-01)
Jhu, Jhe-Ciou
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Chang, Ting-Chang
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Chang, Kuan-Chang
;
Yang, Chung-Yi
;
Chou, Wu-Ching
In this letter, protons (hydrogen ions, H+ ions) transport-induced unstable transient electrical characteristics were found and studied in the etching-stop-layer in via-contact-type amorphous-indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) for the first time. By applying negative gate bias stress, more water molecules will be absorbed on the surface of the passivation layer, and thus the transmission of net protons in the etching-stop will increase. The proton transport model established in this letter can effectively analyze the a-IGZO TFTs instability using the threshold voltage (VT) determined from the current-voltage measurements, and which is unstable in a moist environment.
N2O Plasma Treatment Suppressed Temperature-dependent Point Defects Formation with Amorphous Indium-Gallium-Zinc-Oxide Thin Film Transistors
(2012)
Jhu, Jhe-Ciou
;
Chang, Ting-Chang
;
Chang, Geng-Wei
;
Syu, Yong-En
;
Tsai, Tsung-Ming
Abnormal sub-threshold leakage current is observed at high temperature in amorphous Indium-Gallium-Zinc-Oxide Thin Film Transistors (a-IGZO TFTs). To confirm this phenomenon\'s dependence on the defects of a-IGZO active layer, this paper examines a device fabricated with N2O plasma treatment at a-IGZO film. This phenomenon only appears in the as-fabricated device, but not in the device with N2O plasma treatment, which is experimentally verified. N2O plasma treatment of a-IGZO TFTs enhance the thin film bonding strength, which could suppress the formation of temperature-dependent point defects. The point defects could be generated from oxygen atoms leaving their original sites above 400K. The N2O plasma treatment devices have better stability performance than as-fabricated devices. The results suggested that the density of point states for a-IGZO TFTs with N2O plasma treatment is much lower than that as-fabricated. The N2O plasma repairs the point defect to suppress temperature-dependent sub-threshold leakage current.
N2O plasma treatment suppressed temperature-dependent sub-threshold leakage current of amorphous indium-gallium-zinc-oxide thin film transistors
(2013-09-01)
Chang, Geng-Wei
;
Chang, Ting-Chang
;
Jhu, Jhe-Ciou
;
Tsai, Tsung-Ming
;
Syu, Yong-En
N2O plasma treatment suppressed the temperature-dependent sub-threshold leakage current of amorphous indium-gallium-zinc-oxide thin film transistors (a-IGZO TFTs). For untreated devices, the transfer curve exhibited abnormal electrical properties at high temperature. The abnormal electrical properties are explained by the energy band diagrams for both forward and reverse sweep. Above 400 K, holes can be generated from trap-assisted transition, and drift to the source side which induces source barrier lowering. The source side barrier lowering enhances electron injection from the source to channel and causes an apparent sub-threshold leakage current. This phenomenon, which is experimentally verified, only appears in the device without N2O plasma treatment, but not in the device with N2O plasma treatment. The results suggested that the density of states for a-IGZO with N2O plasma treatment is much lower than that without plasma treatment. (C) 2012 Elsevier B.V. All rights reserved.
Reduction of defect formation in amorphous indium-gallium-zinc-oxide thin film transistors by N2O plasma treatment
(2013-11-28)
Jhu, Jhe-Ciou
;
Chang, Ting-Chang
;
Chang, Geng-Wei
;
Tai, Ya-Hsiang
;
Tsai, Wu-Wei
An abnormal sub-threshold leakage current is observed at high temperature in amorphous indium-gallium-zinc-oxide thin film transistors (a-IGZO TFTs). This phenomenon occurs due to a reduced number of defects in the device's a-IGZO active layer after the device has undergone N2O plasma treatment. Experimental verification shows that the N2O plasma treatment enhances the thin film bonding strength, thereby suppressing the formation of temperature-dependent holes, which are generated above 400 K by oxygen atoms leaving their original sites. The N2O plasma treatment devices have better stability performance than as-fabricated devices. The results suggest that the density of defects for a-IGZO TFTs with N2O plasma treatment is much lower than that in as-fabricated devices. The N2O plasma treatment repairs the defects and suppresses temperature-dependent sub-threshold leakage current. (C) 2013 AIP Publishing LLC.
Suppress temperature instability of InGaZnO thin film transistors by N2O plasma treatment, including thermal-induced hole trapping phenomenon under gate bias stress
(2012-04-30)
Chang, Geng-Wei
;
Chang, Ting-Chang
;
Jhu, Jhe-Ciou
;
Tsai, Tsung-Ming
;
Syu, Yong-En
An abnormal subthreshold leakage current is observed at high temperature, which causes a notable stretch-out phenomenon in amorphous InGaZnO thin film transistors (a-IGZO TFTs). This is due to trap-induced thermal-generated holes accumulating at the source region, which leads to barrier lowering on the source side and causes an apparent subthreshold leakage current. In order to obtain superior thermal stability performance of a-IGZO TFTs, conducting N2O plasma treatment on active layer was expected to avert defects generation during SiO2 deposition process. Reducing defects generation not only suppresses subthreshold current stretch-out phenomenon but also significantly improves the bias stress stability in a-IGZO TFTs at high temperature. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4709417]
Temperature-Dependent Instability of Bias Stress in InGaZnO Thin-Film Transistors
(2014-06-01)
Chang, Geng-Wei
;
Chang, Ting-Chang
;
Jhu, Jhe-Ciou
;
Tsai, Tsung-Ming
;
Chang, Kuan-Chang
The instability of the gate bias and drain bias stresses is observed at high temperature in amorphous InGaZnO thin-film transistors (a-IGZO TFTs). The transfer characteristics of a-IGZO TFTs at different temperatures are also investigated in this paper. The transfer curve exhibits an apparent subthreshold current stretchout phenomenon at high temperature. The stretchout phenomenon becomes more serious with the increase of the temperature. In addition, thermally induced holes are accumulated by the negative gate voltage and get trapped in the gate dielectric or at the dielectric/channel interface at high temperature. The negative threshold voltage shifts with stress time and this is because the trapped holes induce more electrons. For drain bias stress at high temperature, the transfer curve exhibits an apparent shift during drain bias stress at high temperature compared with the same at room temperature. At high temperature, thermally induced holes are trapped in the gate insulator, especially near the drain region. Capacitance-voltage measurements have been used to prove the nonuniform hole-trapping phenomenon. Furthermore, the simulation of the capacitance-voltage and current-voltage curves also have been applied to confirm the hole-trapping distribution. The obtained results clarify that the instability is caused by nonuniform hole-trapping phenomenon.