Abstract:We carried out hydrogen injection in amorphous InGaZnO (a-IGZO) by hot isostatic pressing (HIP) treatment under different pressures ranging from 10 to 1000 bar and investigated the stable site of hydrogen in a-IGZO. The HIP process efficiently injected hydrogen in the whole sample without the formation of indium clusters. Despite oxygen annealing, hydrogenated a-IGZO maintained a high electrical conductivity (n∼1019 cm−3 and μ∼16 cm2/V s) without any noticeable physical degradation. In this paper, we discuss t… Show more
“…Highly oriented phases of XRD peaks were measured, even though the ZnO was deposited by sputtering at room temperature. The full-width at half-maximum (FWHM) of XRD spectra are comparable with the data of ZnO published in literature 34 , 35 , while the IGZO has an amorphous structure 36 . Figure 4 ( a ) SIMS depth profile of ZnO on HfO 2 /TiO 2 /SiO 2 stacked gate dielectrics, ( b ) Cross-sectional TEM and ( c ) XRD spectra of ZnO/high-κ/TaN structure on flexible PEN substrate.…”
High mobility thin-film transistor (TFT) is crucial for future high resolution and fast response flexible display. Remarkably high performance TFT, made at room temperature on flexible substrate, is achieved with record high field-effect mobility (μ
FE) of 345 cm2/Vs, small sub-threshold slope (SS) of 103 mV/dec, high on-current/off-current (I
ON/I
OFF) of 7 × 106, and a low drain-voltage (VD) of 2 V for low power operation. The achieved mobility is the best reported data among flexible electronic devices, which is reached by novel HfLaO passivation material on nano-crystalline zinc-oxide (ZnO) TFT to improve both I
ON and I
OFF. From X-ray photoelectron spectroscopy (XPS) analysis, the non-passivated device has high OH-bonding intensity in nano-crystalline ZnO, which damage the crystallinity, create charged scattering centers, and form potential barriers to degrade mobility.
“…Highly oriented phases of XRD peaks were measured, even though the ZnO was deposited by sputtering at room temperature. The full-width at half-maximum (FWHM) of XRD spectra are comparable with the data of ZnO published in literature 34 , 35 , while the IGZO has an amorphous structure 36 . Figure 4 ( a ) SIMS depth profile of ZnO on HfO 2 /TiO 2 /SiO 2 stacked gate dielectrics, ( b ) Cross-sectional TEM and ( c ) XRD spectra of ZnO/high-κ/TaN structure on flexible PEN substrate.…”
High mobility thin-film transistor (TFT) is crucial for future high resolution and fast response flexible display. Remarkably high performance TFT, made at room temperature on flexible substrate, is achieved with record high field-effect mobility (μ
FE) of 345 cm2/Vs, small sub-threshold slope (SS) of 103 mV/dec, high on-current/off-current (I
ON/I
OFF) of 7 × 106, and a low drain-voltage (VD) of 2 V for low power operation. The achieved mobility is the best reported data among flexible electronic devices, which is reached by novel HfLaO passivation material on nano-crystalline zinc-oxide (ZnO) TFT to improve both I
ON and I
OFF. From X-ray photoelectron spectroscopy (XPS) analysis, the non-passivated device has high OH-bonding intensity in nano-crystalline ZnO, which damage the crystallinity, create charged scattering centers, and form potential barriers to degrade mobility.
“…However, It was reported that hydrogen plays not only as a shallow donor 21 but also as a scattering center in the conduction path. 22,23 Therefore, the carrier scattering induced by hydrogen is one possible reason for the decrease in carrier mobility mentioned above. The free hydrogen and hydrogen contained compounds in a sputtering chamber and in a sputtering target can play as the sources for hydrogen in IGZO film.…”
We report two measurement methods, named positive gate pulse mode (PGPM) and double sweeping mode (DSM), which can estimate the hysteresis induced by hole trapping in a gate insulator ( V hole ) and by defect creation in the IGZO channel ( V defect ). The effects of IGZO deposition temperature and of stress temperature on defect creation in the channel under negative bias and illumination stress (NBIS) are investigated. The results show that high deposition temperature of IGZO reduces defect creation in the channel under NBIS. The average activation energy for hole trapping in a GI under NBIS has been calculated to be 0.39 eV. InGaZnO (IGZO) thin-film transistors (TFTs) with field effect mobility >10 cm 2 /(V · s) are now used in high definition, large area ether active matrix liquid crystal displays (AMLCD) and active matrix organic light emitting diode displays (AMOLED).1,2 However, the reliability of IGZO TFTs under negative bias and illumination stress (NBIS) still requires improvement. Three possible reasons for NBIS instability in IGZO TFTs have been reported: (i) hole trapping in a gate insulator (GI), 3,4 (ii) donor like defect creation in the IGZO channel, [5][6][7] and (iii) electron trapping at a back channel interface. 8 Many efforts to improve NBIS reliability of IGZO TFT have been reported. 9-14 Hole trapping at front channel interface could be reduced by using AlO x as a gate insulator 9 or by using TiO 2 as a hole blocking layer. 14 The donor like state creation could be reduced by annealing IGZO TFTs in a high pressure water vapor, 10 wet O 2 , 11 hydrogen environment. 12 An AlO x , SrO x passivation layer could be used to suppress deep subgap defects in the IGZO channel. 13 In our previous study, 8 both hole trapping in a GI and donor like state creation in an IGZO channel induced hysteresis (V h ) in an IGZO TFT under NBIS. However, unlike a-Si TFT, the NBIS degradation mechanism in IGZO TFT is not consistent. It depends on the TFT structure, 15 the IGZO composition 16 and the fabrication process.17 Therefore, an understanding of the contribution of hole trapping in a GI and donor like state creation in an IGZO channel to V h is essential in the work to improve oxide TFT stability.Capacitance-voltage measurement is usually used to detect defect creation in the IGZO channel. 18,19 Subthreshold voltage swing [Ss = dV g /d log I D (V/decade)] could also be used to estimate the total number of generated defects ( N defect ) using the equation:[1]The threshold voltage shift induced by generated defects ( V defect ) can be calculated using the following equation:where C i is gate capacitance per unit area, q is the elementary charge, K is the Boltzmann constant and T is the absolute temperature (K). However, to the best of our knowledge, there is no direct method for separately measuring of hysteresis induced by trapped hole in a gate insulator ( V hole ) and hysteresis induced by defect creation in a channel ( V defect ). In this study, we demonstrate our developed measurement method, referred to i...
“…For hydrogen treatment, hot isostatic pressing (HIP) was used. The HIP method injects hydrogen into the samples more effectively under high pressure and temperature without damage, whereas hydrogen plasma treatment can cause surface damage due to the high reaction energy …”
There have been many studies of ferromagnetism in ZnCoO, and the results have been controversial. Secondary phases, such as Co oxides and Co metal clusters, in ZnCoO are easily produced during treatment, but the formation conditions are not well understood. We fabricated samples under hydrogen-injection conditions at different heat-treatment temperatures and examined the conditions by using synchrotron X-ray analysis under which Co 3 O 4 appeared or was transformed into Co metal. We investigated the transforming process of the ferromagnetic origin from intrinsic to extrinsic nature via intermediate region competition by Co−H−Co and Co metal cluster and suggest conditions that induce ferromagnetic spin ordering in ZnCoO due to Co−H−Co complexes through hydrogen mediation.
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