ITO-Channel Ferroelectric-Gate Thin Film Transistor with Large On/off Current Ratio

Abstract

AbstractIndium tin oxide (ITO)-channel ferroelectric-gate thin film transistor (TFT) with large on/off current ratio is demonstrated by using mechanical polishing process to planarize the surface of ferroelectric bottom gate insulator (Bi,La)4Ti3O12 (BLT). It is shown that the mechanical polishing of the sol-gel derived polycrystalline ferroelectric BLT films causes no degradation in electrical properties. ITO channel layer was then deposited on the planarized BLT gate insulator to fabricate ferroelectric-gate TFTs. The off-current of the ITO/BLT TFT fabricated with the polishing process is drastically reduced to around 10−12 A, which is four orders of magnitude lower than that of the TFT fabricated without the polishing process. The obtained on/off current ratio is more than 107. In addition, a subthreshold voltage swing as small as 200 mV/decade was obtained.