Characteristics of Thin Film Transistor Using SrTiO_3 Thin Film for HDTV

摘要

In this paper, the a-Si:H TFT using ferroelectric of SrTiO_3 as a gate insulator is fabricated on glas s. Ferroelctric increases on-current, decreases threshold voltage of TFT and also can improve brea kdown characteristics. First, SrTiO_3 thin film is deposited by e-beam evaporation. Dielectric characteristics of deposited SrTiO_3 films are very good because dielectric constant shows 60 - 100 and breakdown electric field are 1 MV/cm. The a-SiN:H has optical band gap of 2.61 eV, refractive ind ex of 1.8 - 2.0 and resistivity of 10~(13) - 10~(15) Ωcm, respectively. The TFT using ferroelectric is consisted of double layer gate insulator, because the ferroelectric thin film has bad adhesion with a-SiH thin film. TFT using ferroelectric has channel length of 20 μm and channel width of 200 μm. And it shows that drain current is 3.4μA at 20 gate voltage, I_(on)/I_(off) is a ratio of 10~5 - 10~8 and V_(th) is 4 - 5 volts, respectively. If properties of the ferroelectric thin film are improved more than ever, the performance of TFT using this ferroelectric thin film shall be advanced.