It was investigated how the amorphous indium-gallium-zinc-oxide (a-IGZO) channel of a back-gate of thin film transistor (TFT) is affected by the deposition of silicon oxide layers on their top surfaces by radio frequency magnetron sputtering. Preliminary investigations showed that the deposition of silicon oxide layer caused damages to the surfaces of pristine silicon wafers resulting in substantial roughening. However, bombardments by the energetic particles involved in the sputtering process seem to have played beneficial roles in that the a-IGZO channel TFTs showed improved performances in respect of the carrier density, field effect mobility, and on-off current ratio. Such improvements are attributed to the modification of the a-IGZO channel to decrease the concentration of oxygen vacancy sites and/or to average the oxygen vacancy sites thereby increasing the carrier concentrations and decreasing the density of trap sites, as revealed in the negative shift of the threshold voltage. On the other hand, such channel modification by the passivation process resulted in the slight increase in the subthreshold swing. It is suggested that the a-IGZO channel TFTs can be passivated by simple sputtering process without etch stop layer since the process rather improved the device performances despite some damages to the passivated surfaces.
Bibliographical noteFunding Information:
This work was supported by the Technology Innovation Program ( 10048402 , Development of low damage process and its evaluation technique for OLED display) funded by the Ministry of Trade, Industry & Energy (MI, Korea) . This work was also supported by the IT R&D program of MOTIE/KEIT (No. 10042414 , Development of 8th Generation (2200×2500 mm 2 ) Major Equipment for Transparent Flexible Display in Large Area) and by the LG Display Academic Industrial Cooperation Program.
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All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering