Undoped p-type ZnTe thin film and thin film transistor channel performance

In this study, the p-type Zinc Telluride (ZnTe) thin films were deposited by RF magnetron sputtering technique on the patterned-ITO substrates. The RF-sputtered p-type ZnTe thin films having 201, 308, 362 and 457 nm thicknesses have been characterized before device fabrication. The SEM and XRD analysis showed that increasing film thickness has caused cluster-like growth and presence of ZnO grains, respectively. In addition, the EDS analysis has been used to determine the composition of Zn and Te. The EDS spectra showed that the ZnO grains may contribute to n-type conductivity as well as to p-type conductivity due to the oxygen-rich (ZnO:O) or tellurium-doped (ZnO:Te) structures. The thickness depends root mean sequence (RMS) values of the ZnTe films are 4.60 nm, 14.36 nm, 20.10 nm, and 27.95 nm, respectively. On the other hand, the threshold voltage ( V_th) , subthreshold current ( I_off ), subthreshold slope (SS) and field effect mobility ( μ ) of the p-type ZnTe thin film transistors (TFTs) have investigated depending on channel layer thickness. The increasing film thickness has caused decreasing performance parameters from 9.75 V, 6.20 × 10 –10 A, 1.15 V/dec and 3,30 cm 2 V −1 s −1 to 2.50 V, 3.60 × 10 –10 A, 0.72 V/dec and 1,68 cm 2 V −1 s −1 , respectively. The film having 100 nm thickness has best saturation-current value.