溶胶凝胶法制备以HfO2为绝缘层和ZITO为有源层的高迁移率薄膜晶体管

采用溶胶凝胶法制备了h-k氧化铪HfO₂薄膜, 经500℃退火后, 获得了高透过率、表面光滑、低漏电流和相对高介电常数的HfO₂薄膜. 并采用氧化铪作为绝缘层和锌铟锡氧化物作为有源层成功地制备了底栅顶接触结构薄膜晶体管器件. 获得的薄膜晶体管器件的饱和迁移率大于100 cm²·V^-1·s^-1, 阈值电压为-0.5 V, 开关比为5×10⁶, 亚阈值摆幅为105 mV/decade. 表明采用溶胶凝胶制备的薄膜晶体管具备高的迁移率, 其迁移率接近低温多晶硅薄膜晶体管的迁移率.

High mobility thin-film transistor with solution-processed hafnium-oxide dielectric and zinc-indium-tin-oxide semiconductor

In this paper, bottom-gate-top-contact structured thin-film transistors (TFTs) are fabricated by solution-processing of hafnium oxide (HfO₂) dielectrics and zinc-indium-tin-oxide (ZITO) semiconductors. Solution-processed HfO₂ films are annealed at different temperatures, and the 500℃ annealed HfO₂ dielectrics can exhibit optimizing film properties such as smooth surfaces (the RMS value of HfO₂ films is less than 1 nm), low leakage current density (1.25×10^-7 A/cm² at 1 MV/cm), high transmittance (above 80% at the wavelength ranging from 400 to 800 nm) and high relative dielectric constant (about 12). The smooth surface of HfO₂ dielectrics is attributed to the decreased charge trapping states at the interface between the HfO₂ dielectrics and ZITO semiconductors, and thus improves the device electrical performance and stability. Hence, TFT devices of HfO₂ dielectrics annealed at 500℃ show a high saturated field effect mobility of more than 100 cm²·V^-1·s^-1 a low threshold voltage of -0.5 V, an on-to-off current ratio of 5×10⁶ and a small subthreshold swing of 105 mV/dec. An almost negligible threshold voltage shift is observed under a positive bias stress for 1000 s, indicating the excellent stability of HfO₂ TFT devices.