Al-Zn-Sn-O Thin Film Transistors with Top and Bottom Gate Structure for AMOLED

Doo-Hee CHO  Sang-Hee Ko PARK  Shinhyuk YANG  Chunwon BYUN  Min Ki RYU  Jeong-Ik LEE  Chi-Sun HWANG  Sung Min YOON  Hye Yong CHU  Kyoung Ik CHO  

IEICE TRANSACTIONS on Electronics   Vol.E92-C    No.11    pp.1340-1346
Publication Date: 2009/11/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E92.C.1340
Print ISSN: 0916-8516
Type of Manuscript: Special Section INVITED PAPER (Special Section on Electronic Displays)
thin film transistor,  oxide,  AMOLED,  transparent,  

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We have fabricated the transparent bottom gate and top gate TFTs using new oxide material of Al-Zn-Sn-O (AZTO) as an active layer. The AZTO active layer was deposited by RF magnetron sputtering at room temperature. Our novel TFT showed good TFT performance without post-annealing. The field effect mobility and the sub-threshold swing were improved by the post-annealing, and the mobility increased with SnO2 content. The AZTO TFT (about 4 mol% AlOx, 66 mol% ZnO, and 30 mol% SnO2) exhibited a mobility of 10.3 cm2/Vs, a turn-on voltage of 0.4 V, a sub-threshold swing of 0.6 V/dec, and an on/off ratio of 109. Though the bottom gate AZTO TFT showed good electrical performance, the bias stability was relatively poor. The bias stability was significantly improved in the top gate AZTO TFT. We have successfully fabricated the transparent AMOLED panel using the back-plane composed with top gate AZTO TFT array.