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报道了不同厚度Ta2O5栅绝缘层对氧化锌薄膜晶体管器件性能的影响。在室温下用射频磁控溅射分别制备了100,85,60,40 nm厚度的Ta2O5薄膜作为绝缘层的一组底栅氧化锌薄膜晶体管器件。从实验结果可以得出如下结论:随着Ta2O5栅绝缘层厚度的增加,相应器件的场效应迁移率下降,其数值分别是50.5,59.3,63.8,71.2 cm2/V.s,对应100,85,60,40 nm厚度的绝缘层。从原子力显微图像可以看到,Ta2O5薄膜表面粗糙度随着薄膜厚度的减小而降低,这是场效应迁移率得以提高的主要原因。而100,85,60,40 nm不同厚度的绝缘层相应器件的开关电流比分别是1.2×105,4.8×105,3.2×104,7.2×103,其阈值电压分别为1.9,1.5,1.2,0.9 V。从各项性能综合考虑,85 nm厚度的Ta2O5栅绝缘层所制备的薄膜晶体管器件具有最佳性能。
The effects of Ta2O5 gate insulating layers with different thicknesses on the performance of ZnO thin film transistor devices are reported. A set of bottom gate ZnO thin film transistor devices with 100, 85, 60 and 40 nm thick Ta2O5 films as insulating layers were prepared by RF magnetron sputtering at room temperature. From the experimental results, we can draw the following conclusions: With the increase of the thickness of Ta2O5 gate insulating layer, the field effect mobility of the corresponding devices decreases, the values are 50.5, 59.3, 63.8, 71.2 cm2 / Vs, corresponding to 100, 85, 40 nm thick insulation. It can be seen from the atomic force microscopy images that the surface roughness of the Ta2O5 thin film decreases as the film thickness decreases, which is the main reason for the increase of the field effect mobility. While the switching current ratios of the corresponding devices with different thicknesses of 100, 85, 60 and 40 nm are 1.2 × 105, 4.8 × 105, 3.2 × 104 and 7.2 × 103 respectively, and their threshold voltages are 1.9, 1.5, 1.2, 0.9 V. Considering the various performances, the thin film transistor devices prepared by Ta2O5 gate insulating layer with the thickness of 85 nm have the best performance.