A Novel Amorphous InGaZnO Thin Film Transistor Structure without Source/Drain Layer Deposition

In this paper, new structured amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) without conventional source/drain (S/D) layer deposition were introduced. The S/D layers were formed in a-IGZO channel layer by hydrogen (H-2) plasma treatments. As the increased plasma treatment time, the resistivity of plasma treated a-IGZO as S/D decreased drastically from 10(4) to 4.8 x 10(-3) Omega cm due to the carrier generation by plasma treatment for 240 s. The carrier concentration mechanism of the H2 plasma treated sample could be attributed to the preferential sputtering of oxygen by H-2 bombardment due to formation of an oxygen vacancy and removal of adsorbed O-2. The new proposed TFTs exhibited a field-effect mobility of 7.14 cm(2) V-1 s(-1), an on/off ratio of 7.95 x 10(6), a threshold voltage of 0.94 V, and a subthreshold swing of 1.06 V/decade. These results demonstrated the possibility of low cost TFT process because S/D electrode deposition was unnecessary. (C) 2009 The Japan Society of Applied Physics