High-performance dual-layer channel indium gallium zinc oxide thin-film transistors fabricated in different oxygen contents at low temperature

In this work, fully transparent dual-layer channel amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs) are fabricated on glass substrates at low temperature. Dual-layer channel a-IGZO TFTs are studied by changing the partial pressure of oxygen while sputtering IGZO layers for comparison with single-layer channel TFTs which are fabricated with a constant oxygen content. All four types of dual-layer channel TFT sample demonstrate better performance, on-to-off ratios of similar to 10(8) and low subthreshold swing (SS) of less than 200mV/decade, than the single-layer ones. TFTs with two layers, a low-oxygen layer and a high-oxygen layer formed using oxygen partial pressures of 0.01 and 0.05 Pa, respectively demonstrate relatively better performance with a mobility of more than 60cm(2)V(-1)s(-1). Among them, the TFTs with a channel layer thickness ratio of 3 : 1 show the best transfer characteristics with a high on-to-off current ratio (I-on/off) of 1.8 x 10(8) and a low SS of 135mV/decade. (C) 2014 The Japan Society of Applied Physics