Effect of indium composition ratio on solution-processed nanocrystalline InGaZnO thin film transistors

Kim, Chan Yun; Ahn, Byung Du; Shin, Hyun Soo; Jeong, Woong Hee; Kim, Hee Jin; Kim, Hyun Jae

doi:10.1063/1.3151827

Cited by 211 publications

(134 citation statements)

References 14 publications

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“…1(a-c)). Crucially, they demonstrated that such a device could exhibit high mobility, stimulating much work on this system [24,25]. A second milestone on the road towards oxide electronics can be seen as the observation of the integer [26] and, more recently, fractional [27] quantum Hall effects in ZnO/MgZnO heterostructures by Tsukazaki et al (Fig.…”

Section: Introductionmentioning

confidence: 99%

Conductivity in transparent oxide semiconductors

King

Veal

2011

J. Phys.: Condens. Matter

225

180

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Abstract. Despite an extensive research effort for over 60 years, an understanding of the origins of conductivity in wide band-gap transparent conducting oxide (TCO) semiconductors remains elusive. While TCOs have already found widespread use in device applications requiring a transparent contact, there are currently enormous efforts to (i) increase the conductivity of existing materials, (ii) identify suitable alternatives, and (iii) attempt to gain semiconductor-engineering levels of control over their carrier density, essential for the incorporation of TCOs into a new generation of multifunctional transparent electronic devices. These efforts, however, are dependent on a microscopic identification of the defects and impurities leading to the high unintentional carrier densities present in these materials. Here, we review recent developments towards such an understanding. While oxygen vacancies are commonly assumed to be the source of the conductivity, there is increasing evidence that this is not a sufficient mechanism to explain the total measured carrier concentrations. In fact, many studies suggest that oxygen vacancies are deep, rather than shallow, donors, and their abundance in as-grown material is also debated. We discuss other potential contributions to the conductivity in TCOs, including other native defects, their complexes, and in particular hydrogen impurities. Convincing theoretical and experimental evidence is presented for the donor nature of hydrogen across a range of TCO materials, and while its stability and the presence of interstitial and substitutional species are still somewhat open questions, it is one of the leading contenders for unintentional conductivity in TCOs. We also review recent work indicating that the surfaces of TCOs can support very high carrier densities, opposite to the case of conventional semiconductors. In thin-film materials/devices and, in particular, nanostructures, the surface can have a large impact on the total conductivity in TCOs. We discuss models that attempt to explain both the bulk and surface conductivity based on features of the bulk band structure common across the TCOs, and compare these materials to other semiconductors. Finally, we briefly consider transparency in these materials, and its interplay with conductivity. Understanding this interplay, as well as the microscopic contenders for the conductivity of these materials, will prove essential to the future design and control of TCO semiconductors, and their implementation into novel multifunctional devices.

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Section: Introductionmentioning

confidence: 99%

Conductivity in transparent oxide semiconductors

King

Veal

2011

J. Phys.: Condens. Matter

225

180

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“…Therefore, the optimal Ga ratio ranges from 0.4 to 0.5 at a fixed In to Zn ratio of 1:1. Nt values were obtained using following equation: [13] IGZO-TFTs with a Ga ratio of 0.5 were also measured after different annealing temperatures of 300°C and 350°C, which are lower than the previous temperature of 400°C, as shown in Fig. 5.…”

Section: Resultsmentioning

confidence: 99%

“…Solution-processed IGZO films crystallized with nanosized grains were reported because of the structure of InO 2 layers and GaO(ZnO)m blocks, which are similar to the c-axis orientation of ZnO under the influence of Ga addition [13]. On the other hand, the crystalline structure for appropriate stacking was not observed because the content of In ions that disturb matching is relatively higher than that reported elsewhere [12][13][14]. Hence, all the IGZO films had an amorphous structure without any peaks.…”

Section: Methodsmentioning

confidence: 99%

Effects of Ga Composition Ratio and Annealing Temperature on the Electrical Characteristics of Solution-processed IGZO Thin-film Transistors

Lee¹,

Park²,

Kim³

et al. 2014

JSTS:Journal of Semiconductor Technology and Science

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Abstract-Bottom gate thin-film transistors were fabricated using solution processed IGZO channel layers with various gallium composition ratios that were annealed on a hot plate. Increasing the gallium ratio from 0.1 to 0.6 induced a threshold voltage shift in the electrical characteristics, whereas the molar ratio of In:Zn was fixed to 1:1. Among the devices, the IGZO-TFTs with gallium ratios of 0.4 and 0.5 exhibited suitable switching characteristics with low off-current and low SS values. The IGZO-TFTs prepared from IGZO films with a gallium ratio of 0.4 showed a mobility, on/off current ratio, threshold voltage, and subthreshold swing value of 0.1135 were also fabricated. Annealing at lower temperatures induced a positive shift in the threshold voltage and produced inferior electrical properties.

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“…After post-annealing,, a carrier concentration increases and disordered atomic structures are rearranged into dense atomic structures, leading to the decrease of trap density for electrons and the increase of electron mobility 20) . The improvement of TFT device performance through doping and variation of target composition of IGZO thin film has been also reported 21,22) . Recently, the electrical performances and interfacial stability between metal Mo, Al, and Cu electrode and amorphous IGZO (a-IGZO) semiconductor were studied before and after air-annealing 23) .…”

Section: Introductionmentioning

confidence: 99%

Diffusion Behaviors and Electrical Properties in the In-Ga-Zn-O Thin Film Deposited by Radio-frequency Reactive Magnetron Sputtering

Lee¹,

Choi²,

Lee³

2015

Journal of the Korean institute of surface engineering

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We investigated the diffusion behaviors, electrical properties, microstructures, and composition of In-GaZn-O (IGZO) oxide thin films deposited by radio frequency reactive magnetron sputtering with increasing annealing temperatures. The samples were deposited at room temperature and then annealed at 300, 400, 500, 600 and 700 o C in air ambient for 2 h. According to the results of time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy, no diffusion of In, Ga, and Zn components were observed at 300, 400, 500, 600 o C, but there was a diffusion at 700 o C. However, for the sample annealed at 700 o C, considerable diffusion occurred. Especially, the concentration of In and Ga components were similar at the IGZO thin film but were decreased near the interface between the IGZO and glass substrate, while the concentration of Zn was decreased at the IGZO thin film and some Zn were partially diffused into the glass substrate. The high-resolution transmission electron microscopy results showed that a phase change at the interface between IGZO film and glass substrate began to occur at 500 o C and an unidentified crystalline phase was observed at the interface between IGZO film and glass substrate due to a rapid change in composition of In, Ga and Zn at 700

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Effect of indium composition ratio on solution-processed nanocrystalline InGaZnO thin film transistors

Cited by 211 publications

References 14 publications

Conductivity in transparent oxide semiconductors

Conductivity in transparent oxide semiconductors

Effects of Ga Composition Ratio and Annealing Temperature on the Electrical Characteristics of Solution-processed IGZO Thin-film Transistors

Diffusion Behaviors and Electrical Properties in the In-Ga-Zn-O Thin Film Deposited by Radio-frequency Reactive Magnetron Sputtering

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