TiSiOx gate dielectrics produced by reactive sputtering for high performance InGaZnO thin film transistors

High dielectric constant TiSiOx thin films are produced by reactive sputtering under different oxygen partial pressure ratio (PO2) from 15% to 30%. All the TiSiOx films show an excellent transmittance value of almost 95%. The TiSiOx film has a low leakage current density by optimizing oxygen partial pressure, and the leakage current density of TiSiOx film under PO2 of 20% is 4.88×10−7 A/cm2 at electrical field strength of 2 MV/cm. Meanwhile, their associated InGaZnO thin-film transistors (IGZO-TFTs) with different PO2 TiSiOx thin films as gate insulators are fabricated. IGZO-TFTs under PO2 of 20% shows an optimized electrical performance, and the threshold voltage, sub-threshold swing, field effect mobility and Ion/Ioff ratio of this device are 2.22 V, 0.33 V/decade, 29.3 cm2/V s and 5.03×107, respectively. Moreover, the density of states (DOS) is calculated by temperature-dependent field-effect measurement. The enhancements of electrical performance and temperature stability are attributed to better active/insulator interface and smaller DOS.