氮掺铟锡锌薄膜晶体管的制备及其光电特性

以P型100硅作为衬底,采用射频磁控溅射技术,在室温下制备了氮掺杂氧化铟锡锌薄膜晶体管(ITZO TFTs),研究了氮气流量对氧化铟锡锌薄膜晶体管结构、光学、电学特性以及稳定性的影响。实验结果表明:在不同氮气流量条件下制备的氧化铟锡锌薄膜均为非晶态,在可见光范围内的平均透过率均在90%左右,光学带隙数值在3.28~3.32 e V之间变化。在氮气流量为4 m L/min时制备的ITZO TFTs,有源层与栅极电介质界面处的界面态密度(N~(max)_s)仅为4.3×10~(11)cm~(-2),场效应迁移率(μ_(FE))为18.72 cm~2/(V·s),开关比(I_(on/off))为10~6,亚阈值摆幅(S)为0.39 V/dec,电学性能最优。栅极正偏压应力测试结果表明,该器件具有最强的稳定性。因此,适量的氮掺杂可有效地实现器件氧空位的钝化,降低器件的界面态密度,提高ITZO TFTs的电学性能及稳定性。

Fabrication and Electrical and Optical Properties of Nitrogen-doped In-Sn-Zn Oxide Thin-film Transistors

In-Sn-Zn oxide thin-film transistors were deposited at different nitrogen flow rates on P-Si<100> substrate by RF magnetron sputtering. The influence of nitrogen on the structure, optical and electrical properties and stabilities of ITZO TFTs was studied. The results show that nitrogen has no obvi-ous effect on the structure of ITZO films and all thin films are amorphous. The average transmittance of all ITZO films approach or exceed 90% in the visible region and the optical band gaps are 3. 28-3. 32 eV. When the nitrogen flow rates increase to 4 mL/min during the sputter deposition, the ITZO TFTs with low interface state density(~4. 3 × 1011 cm-2 ) show excellent electrical properties, the sub-thresh-old swing is 0. 39 V/dec and on/off ratio is 106 operated with the field-effect mobility (μFE ) of 18. 72 cm2/(V?s). Moreover, the TFTs show better stability than others in the positive gate bias stress test. Overall, the suitable addition of nitrogen can improve the electrical performance and the stability of the ITZO TFTs by the passivation of oxygen vacancies and the drop of interface state density.