Effects of Substrate Heating on the Amorphous Structure of InGaZnO Films and the Electrical Properties of Their Thin Film Transistors

Moon, Miri; Na, Sekwon; Jeon, Haseok; An, Cheol Hyun; Park, Kyung; Jung, Donggeun; Kim, Hyoungsub; Lee, Young-Boo; Lee, Hoo-Jeong

doi:10.1143/apex.3.111101

Cited by 10 publications

(6 citation statements)

References 12 publications

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“…In the legend S means “solution processed” (data compiled from refs. 66, 78–276 only dealing with GIZO TFTs, the ones corresponding to solution process are in Tables 2a, b and c.…”

Section: Recent Progress Of N‐type Oxide Tftsmentioning

confidence: 99%

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

2012

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Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

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“…In the legend S means “solution processed” (data compiled from refs. 66, 78–276 only dealing with GIZO TFTs, the ones corresponding to solution process are in Tables 2a, b and c.…”

Section: Recent Progress Of N‐type Oxide Tftsmentioning

confidence: 99%

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

2012

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“…Thus, the results of the EF‐SAED analysis clearly demonstrate the effect of substrate heating and support the results of HR‐TEM, confirming our expectation that deposition on a heated substrate would facilitate atomic ordering by allowing the adsorbed atoms to diffuse more readily and construct an atomic structure with enhanced atomic order . In addition, these results are consistent with those of our previous study that substrate heating enhanced the atomic order …”

Section: Resultsmentioning

confidence: 99%

The effects of a combined thermal treatment of substrate heating and post‐annealing on the microstructure of InGaZnO films and the device performance of their thin film transistors

Moon

Jeon

et al. 2012

Surface & Interface Analysis

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This study examined the possibility of engineering the microstructure of InGaZnO films and enhancing the device performance of their thin film transistors by combining the thermal treatments of substrate heating and post‐annealing. Microstructure characterization using high‐resolution transmission electron microscopy and energy‐filtered selected area electron diffraction helped us to unravel a systematic improvement in atomic order induced by substrate heating. Hall measurement analysis confirmed that the electrical properties (carrier concentration and electron mobility) varied very sensitively with the thermal treatments. The combined thermal treatments were found to effectively enhance the overall device performance of the transistors, and the sample deposited at 200 °C and post‐annealed at 400 °C showed the best transistor characteristics with a saturation mobility (μsat) of nearly 26 cm2/V s. Copyright © 2012 John Wiley & Sons, Ltd.

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“…As the Zn content increased, the atomic order probably enhanced and nanocrystalline IGZO emerged, which would lead to a continuous increase in mobility by reducing the trap density. [17][18][19] However, raising the Zn ratio to a level greater than a critical point prompted a drastic phase transformation from nanocrystalline IGZO to columnar ZnO, resulting in a steep drop in electron mobility and a drastic shift in threshold voltage.…”

Section: Microstructure Analysis-mentioning

confidence: 99%

The Effects of Zn Ratio on the Microstructure Electrical Properties of InGaZnO Films

Jeon

Moon

et al. 2011

J. Electrochem. Soc.

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This study examined the effects of the Zn ratio on the microstructure of InGaZnO (IGZO) films and the device performance of their transistors. IGZO films with various Zn ratios were produced by co-sputtering InGaO and ZnO at different ZnO powers. The combination of transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses elucidated that as the Zn ratio increased from 0 to 0.69, the microstructure changed from amorphous IGZO to nanocrystalline IGZO and then to columnar ZnO. The dynamic transitions of the microstructure, in turn, profoundly affected the electrical properties including the mobility and carrier concentration. The sample with a mixing ratio of 0.25:0.2:0.55 (In:Ga:Zn) exhibited the best performance with a mobility of nearly 30 cm 2 /VÁs. Transparent oxide semiconductors (TAOS) have recently gained much attention owing to their technologically important features, including their high electron mobility, high transparency, capability for low temperature processing, etc. These materials are excellent candidates for the active layer of thin film transistors for display applications. 1,2 In particular, amorphous InGaZnO 4 (IGZO) has been the focus of many research and development efforts since Hosono and colleagues first demonstrated the possibility of using it as the active layer of TFTs. 3 Some such studies include the optimization of sputtering conditions (O 2 pressure, sputtering power, etc) and post-annealing conditions. 1,4 Nevertheless, systematic composition engineering of this material by modulating the cation ratio still remains incomplete.For the development of IGZO-based transistors with enhanced device performance, it is important to understand the roles of the main metallic elements (In, Ga, and Zn) of the material. Some recent studies unfolded that as the In ratio increased, the carrier concentration escalated sensitively and thus led to an increase in both the on-current and off-current, suggesting that In played the role of charge carrier generators. 5,6 Increasing the Ga ratio seems to have the opposite effect: With the Ga content increasing, the carrier concentration drastically decreases since Ga suppresses oxygen vacancy formation. 5-10 Thus, the In/Ga ratio is known to be critical for determining the carrier concentration of IGZO films. However, what remains relatively unexplored are the effects of modulating the Zn ratio on the film properties. It would be intriguing to investigate how the microstructure evolves and the electrical properties change as the Zn ratio changes over a wide range.In this study, we delved into the effects of the Zn ratio on the characteristics (microstructure, carrier concentration, and Hall mobility) of IGZO films and the device performance of their TFTs. We produced IGZO films with various Zn ratios via co-sputtering InGaO (IGO) and ZnO at different ZnO target powers. Combining X-ray diffraction (XRD), transmission electron microscopy (TEM), and Hall Effect measurements helped us to fully characterize the evolution of the film microstruct...

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Effects of Substrate Heating on the Amorphous Structure of InGaZnO Films and the Electrical Properties of Their Thin Film Transistors

Cited by 10 publications

References 12 publications

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

The effects of a combined thermal treatment of substrate heating and post‐annealing on the microstructure of InGaZnO films and the device performance of their thin film transistors

The Effects of Zn Ratio on the Microstructure Electrical Properties of InGaZnO Films

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