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Transparent amorphous oxide semiconductor (TAOS) has been reported as a promising material for next-generation displays. Recently, Tomai et al. reported that amorphous indium tin zinc oxide (ITZO) has excellent properties such as high electron mobility, low voltage operation, and high reliability under electrical stress condition. To realize the next generation displays, high-speed operation and high reliability under various stresses are indispensable. For high-speed operation, TAOS thin-film transistors (TFTs) can be achieved by their high electron mobility. However, for high reliability, self-heating effect of TFT under voltage stress is one of the most important issues, especially in high performance TFT fabricated on a substrate with lower thermal conductivity, such as glass and polyethylene terephthalate. In their paper on pp. 1561–1564, Sergent et al. have focused on the scale dependence of self-heating effect on the reliability of ITZO TFT. As a result, they found that the heating temperature increases with increasing channel width under same voltage and current density conditions. It was also confirmed that accumulation of heating becomes evident with increasing channel width. Therefore, the reliability of the TFT with different channel scale is dicussed to clarify the influence of self-heating phenomenon on the reliability.