Our crystalline In–Ga–Zn oxide (IGZO) thin film has a c‐axis‐aligned crystal (CAAC) structure and maintains crystallinity even on an amorphous base layer. Although the crystal has c‐axis alignment, its a‐axis and b‐axis have random arrangement; moreover, a clear grain boundary is not observed. We fabricated a back‐channel‐etched thin‐film transistor (TFT) using the CAAC‐IGZO film. Using the CAAC‐IGZO film, more stable TFT characteristics, even with a short channel length, can be obtained, and the instability of the back channel, which is one of the biggest problems of IGZO TFTs, is solved. As a result, we improved the process of manufacturing back‐channel‐etched TFTs.

Sharp succeeded the production of high performance LCD using IGZO for the first time in the world. With the extraordinary TFT characteristics, IGZO-TFT LCD can realize (1)lower power consumption and (2)higher touch panel performance than a-Si TFT LCD. In this paper, we report the development of IGZO-TFT and new LCD devices.

To clarify the origin of the major donor states in indium gallium zinc oxide (IGZO), we report measurement results and an analysis of several physical properties of IGZO thin films. Specifically, the concentration of H atoms and O vacancies (V O ), carrier concentration, and conductivity are investigated by hard X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, thermal desorption spectroscopy, and Hall effect measurements. The results of these experiments suggest that the origin of major donor states is H occupancy of V O sites. Furthermore, we use first-principles calculations to investigate the influence of the coexistence of V O and H in crystalline InGaO 3 (ZnO) m (m ¼ 1). The results indicate that when H is trapped in V O , a stable complex is created that serves as a shallow-level donor. V C 2014 AIP Publishing LLC.

We have fabricated a back‐channel‐etched TFT using the CAAC‐IGZO film that we developed. As a factor of success in manufacturing stable back‐channel‐etched TFTs, it is considered that CAAC‐IGZO has a strong structure because of its crystallinity. For verification, we have compared the cohesive energy of c‐IGZO and that of a‐IGZO.

We have recently discovered that films of a widely used In–Ga–Zn oxide (IGZO) with have different material composition states when sputter-deposited under different conditions using the same polycrystalline IGZO target. Significant improvements in on-state current and mobility (as high as 40 cm2·V−1·s−1) are obtained. The results of local composition analysis indicate that the deposited film is not composed of any known homogeneous IGZO compound and that the components of this film are separated into two types of nanoparticle regions: one type is composed mainly of GaO x and GaZnO x , which contribute to on/off (switching) characteristics, and the other is composed mainly of InO x and InZnO x , which contribute to on-state characteristics. These regions constitute a new type of oxide semiconductor (OS) film. The nanoparticles with a blurry boundary extend like a cloud, probably complementing one another. We consider that this OS film has a novel composition, which can be described as a “cloud-aligned composite OS” (CAC-OS).