Influence of a highly doped buried layer for HfInZnO thin-film transistors

Hafnium-indium-zinc oxide (HIZO) channel thin-film transistors (TFTs) have been reported with a 12 nm thick indium-zinc oxide (IZO)-buried layer. IZO-buried HIZO TFTs show excellent electrical characteristics and stabilities such as a high mobility (mu(FE)) of similar to 41.4 cm(2) V-1 s(-1) which is three times higher than that of conventional HIZO TFTs and significantly enhanced bias-temperature-induced stability. High mobility could be obtained since the current path is mainly formed on a highly conductive buried layer with a high carrier concentration over 10(18) cm(-3). Enhanced stability could be achieved mainly because the generation of the additional trap state was considerably reduced near the drain region due to a relatively short path since the current flows vertically from a highly conductive buried layer to a drain electrode through the HIZO channel via a relatively low carrier density region.