Zinc tin oxide thin film transistors produced by a high rate reactive sputtering: Effect of tin composition and annealing temperatures
Zinc tin oxide thin film transistors produced by a high rate reactive sputtering: Effect of tin composition and annealing temperatures
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DOI：
10.1002/pssa.201600470
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
K. Niang;Junhee Cho;A. Sadhanala;W. Milne;R. Friend;A. Flewitt
中科院分区：
文献类型：
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作者：
K. Niang;Junhee Cho;A. Sadhanala;W. Milne;R. Friend;A. Flewitt
非晶态氧化锌锡 (a-ZTO) 的化学计量与 Zn2SnO4 和 ZnSnO3 相接近，已使用远程等离子体反应溅射进行沉积，并作为薄膜晶体管 (TFT) 中的沟道层。研究了锡成分和退火温度对薄膜结构和相演化以及 TFT 电性能的影响。 Zn2SnO4在退火温度≥700℃时表现出随机取向的多晶峰，而ZnSnO3在950℃时分解为Zn2SnO4和SnO2。采用 Zn2SnO4 通道的 TFT，在 500 °C 的沉积后退火后，表现出场效应迁移率 ~14 cm2 V−1 s−1 和亚阈值斜率 ~0.6 V dec−1。当沟道中的锡含量增加时，如在 ZnSnO3 中，TFT 的场效应迁移率增加了约 20 cm2 V−1 s−1，但亚阈值斜率略有恶化，达到约 0.8 V dec−1。当沉积后退火温度降低到 300 °C 时，仍然可以实现高达~10 cm2 V−1 s−1 的迁移率，但是，在 IDS-VGS 曲线中观察到显着的肩部以及更高的断态电流。 TFT 特性可以通过光热偏转光谱测量的亚带隙缺陷态和提取的 Urbach 能量来解释。
Amorphous zinc tin oxides (a‐ZTO), which are stoichiometrically close to the Zn2SnO4 and ZnSnO3 phases, have been deposited using remote‐plasma reactive sputtering, and incorporated as the channel layers in thin film transistors (TFTs). The influence of tin composition and annealing temperatures on the structural and phase evolutions of the thin films, and the electrical performances of the TFTs are investigated. Zn2SnO4 exhibited randomly oriented polycrystalline peaks at annealing temperatures ≥700 °C, while ZnSnO3 decomposed into Zn2SnO4 and SnO2 at 950 °C. TFTs employing a Zn2SnO4 channel, after a post‐deposition annealing at 500 °C, exhibited a field effect mobility ∼14 cm2 V−1 s−1 and a sub‐threshold slope ∼0.6 V dec−1. When the tin content was increased in the channel, as in ZnSnO3, TFTs exhibited an increase in field effect mobility ∼20 cm2 V−1 s−1, but with a slight deterioration of sub‐threshold slope to ∼0.8 V dec−1. When the post‐deposition annealing temperature was reduced to 300 °C, a mobility as high as ∼10 cm2 V−1 s−1 was still achieved, however, a significant shoulder in the IDS–VGS curve, together with a higher off‐state current was observed. TFT characteristics are explained by the sub‐bandgap defect states measured by photothermal deflection spectroscopy and the extracted Urbach energies.