We fabricated an inverted-staggered amorphous In–Ga–Zn-oxide (a-IGZO) thin film transistor (TFT) and measured the temperature dependence of its characteristics. A threshold voltage (V th) shift between 120 and 180 °C was as large as 4 V. In an analysis with two-dimensional (2D) numerical simulation, we reproduced the measured result by assuming two types of donor-like states as carrier generation sources. Furthermore, by ab initio molecular dynamics (MD) simulation, we determined the electronic structures of three types of a-IGZO structures, namely, “stoichiometric a-IGZO”, “oxygen deficiency”, and “hydrogen doping”.

We have newly developed a 4.0-in. quarter video graphics array (QVGA) active-matrix organic light-emitting diode (AMOLED) display integrated with gate and source driver circuits using amorphous In–Ga–Zn-oxide (IGZO) thin-film transistors (TFTs). Focusing on a passivation layer in an inverted staggered bottom gate structure, the threshold voltage of the TFTs can be controlled to have “normally-off” characteristics with suppressed variation by using a SiO x layer formed by sputtering with a low hydrogen content. In addition, small subthreshold swing S/S of 0.19 V/decade, high field-effect mobility µFE of 11.5 cm2 V-1 s-1, and threshold voltage V th of 1.27 V are achieved. The deposition conditions of the passivation layer and other processes are optimized, and variation in TFT characteristics is suppressed, whereby high-speed operation in gate and source driver circuits can be achieved. Using these driver circuits, the 4.0-in. QVGA AMOLED display integrated with driver circuits can be realized.

We have developed a 4.0 inch QVGA AMOLED display using amorphous In‐Ga‐Zn‐Oxide TFTs, focusing on a passivation layer. Threshold voltage of the TFTs can be controlled to have “normally off” characteristics by using SiOx with a low hydrogen content. Besides, small subthreshold swing and high saturation mobility are obtained.

We fabricated inverted‐staggered amorphous In‐Ga‐Zn‐O (a‐IGZO) TFTs and measured temperature dependence of the TFT characteristics. A Vth shift between 120°C and 180°C was as large as about 4 V. In the analysis with 2‐D numerical simulation, we could reproduce the measured result by assuming two kinds of donor‐like states as carrier generation sources.

Diamond films were synthesized on a Mo substrate using combustion flame. During cooling process, the most diamond films delaminated from the Mo substrate because of their thermal expansion mismatch. To prevent the delamination, a three-step synthesis method was proposed. The first step was synthesis of the Mo 2 C and the diamond phases on the Mo substrate, and the second and the third steps were synthesis of the diamond phase. The interfacial stress between the film and substrate was calculated by a finite element method. According to the results, the stress in the film made by the method was smaller than that by an one-step synthesis method. The three-step method is useful for synthesizing the diamond film.