Professor Yonsei University Seoul, Republic of Korea
In this study, the oxygen scavenging layer (OSL) was introduced between channel and gate insulator to improve the electrical characteristics even at 200oC fabrication of amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs). The OSL is a layer introduced between the channel layer and the gate insulator layer, which is thinly deposited to absorb oxygen in the effective channel of a-IGZO with annealing process. MgOx was used to make the OSL. The a-IGZO TFTs with OSL, even if annealed at a low-temperature of 200oC, exhibit improved electrical characteristics and stability under positive bias temperature stress (PBTS) compared to those without OSL: field-effect mobility from 8.15 to 16.08 cm2/Vs, subthreshold swing from 0.45 to 0.42 V/decade, on/off current ratio from 3.19 × 108 to 9.53 × 109. A threshold voltage shift under PBTS at 50 oC for 10,000 sec was decreased from + 8.94 V to + 1.98 V. These improvements are attributed to Mg of OSL absorbing oxygen ions in the effective channel layer of a-IGZO.
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.jpg "Hyun Jae Kim, Prof. photo")