Microstructures of ITO films deposited by d.c. magnetron sputtering with H2O introduction

Nishimura, Etsuko; Ohkawa, Hideki; Song, Pung Keun; Shigesato, Yuzo

doi:10.1016/s0040-6090(03)01168-4

Cited by 41 publications

(16 citation statements)

References 7 publications

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“…The incorporation of the impurities is enhanced at a lower deposition rate because the incorporation rate of hydrogen (i.e., number of hydrogen atoms per second) should be constant and determined by their densities in the residual/supplied gases, while a lower deposition rate requires a longer deposition time and consequently incorporate more impurities. Further, as it is reported that incorporation of H/H 2 O stabilizes amorphous phases for (In,Sn) 2 O 3 [15,16], In 2 O 3 [17], etc., it is considered that the amorphous phase of the film deposited at 1 J/cm 2 would be stabilized also by the impurity hydrogen.…”

Section: Resultsmentioning

confidence: 82%

Ultrawide band gap amorphous oxide semiconductor, Ga–Zn–O

et al. 2016

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We fabricated amorphous oxide semiconductor films, a-(Ga 1-x Zn x )O y , at room temperature on glass, which have widely tunable band gaps (E g ) ranging from 3.47-4.12 eV. The highest electron Hall mobility~7 cm 2 V −1 s −1 was obtained for E g =~3.8 eV. Ultraviolet photoemission spectroscopy revealed that the increase in E g with increasing the Ga content comes mostly from the deepening of the valence band maximum level while the conduction band minimum level remains almost unchanged. These characteristics are explained by their electronic structures. As these films can be fabricated at room temperature on plastic, this achievement extends the applications of flexible electronics to opto-electronic integrated circuits associated with deep ultraviolet region.

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Section: Resultsmentioning

confidence: 82%

Ultrawide band gap amorphous oxide semiconductor, Ga–Zn–O

et al. 2016

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“…The smooth surface and fine grain size of the H-ITO anode could be attributed to the termination of -H and -OH, at the ITO anode surface, which disrupts the crystallization of ITO films. 6 The higher nucleation sites, which were created by reactive -H and -OH, could provide an explanation for the formation of fine and uniform grain size of the H-ITO anode film in Fig. 2a.…”

mentioning

confidence: 93%

Effect of Introducing H[sub 2]O Vapor on Properties of RF Sputter-Grown ITO Anode Layer for OLEDs

Kim

Lee

2008

Electrochem. Solid-State Lett.

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We report the effects of introducing H 2 O vapor on the structural, surface, and electrical properties of radio-frequency ͑rf͒ sputtered indium tin oxide ͑ITO͒ anode layer for organic light-emitting diodes ͑OLEDs͒. By introducing H 2 O vapor during rf sputtering, we obtained an ITO anode film with lower resistivity, higher transmittance, and a smoother surface relative to the conventional rf-sputter-grown ITO anode even though it was grown at a substrate temperature of 200°C. Secondary ion mass spectroscopy analysis clearly shows that OH content in the rf-sputter-grown ITO anode film was significantly increased by adding H 2 O vapor. In addition, the current density-voltage-luminance result of an OLED fabricated on an H 2 O-vapor-incorporated ITO anode showed a lower turn-on voltage and higher luminescence than those of OLEDs fabricated on the reference ITO anode. This suggests that the introduction of H 2 O vapor during rf sputtering is an effective technique employed to improve the ITO anode layer for both topand bottom-emitting OLEDs.Indium tin oxide ͓SnO 2 -doped In 2 O 3 ͑ITO͔͒ has been commonly used in organic light-emitting diodes ͑OLEDs͒ and flexible OLEDs as anode materials both academically and commercially, due to its low resistivity and high transmittance in a visible range. 1-3 To obtain a high-quality ITO anode layer, it is necessary to raise glass substrate temperatures up to 300-400°C during the radio-frequency ͑rf͒ sputtering process. However, high substrate temperature could lead to crystallization of the ITO anode film with a preferred orientation and a rough surface. Because protrusions and spikes on the rough ITO surface act as field emission positions, which have higher voltage than their surroundings, it is important to deposit an ITO anode layer with a very smooth surface for high-performance OLEDs. Although the ITO film grown at room temperature has a very smooth surface, it is difficult to apply in OLEDs as anode materials due to the fairly high resistivity. 4 For these reasons, the ITO anode layer grown at a high substrate temperature is required to apply the chemical and mechanical polishing process. To solve those problems, Ishibashi et al. reported that an ITO film with low resistivity could be obtained at a substrate temperature below 200°C by adding H 2 O gas during an inline dc sputtering process. 5 They showed that the addition of H 2 O gas during ITO sputtering resulted in suppression of ITO crystallization and reduction in ITO film resistivity. Although the technique of H 2 O vapor introduction during ITO sputtering has been reported, the effect of H 2 O vapor introduction on properties of ITO anode materials and the use of the H 2 O-incorporated ITO anode in OLEDs has not yet been reported in detail.In this work, we report on growth of the ITO anode with an extremely smooth surface and low resistivity for normal and flexible OLEDs by the addition of H 2 O vapor to ambient Ar during ITO sputtering. The H 2 O-incorporated ITO anode exhibited lower resistivity, higher transmittan...

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“…Nishimura et al, 2003 found that without H 2 O introduction, the as-deposited films exhibited a polycrystalline In 2 O 3 structure, and with H 2 O introduction, the as-deposited films were amorphous with a high concentration of hydrogen by secondary ion mass spectroscopy. Thus, the introduction of H 2 O would reduce the grain size of ITO film or even form amorphous ITO films.…”

Section: Resultsmentioning

confidence: 98%