Ahn Byung Du, Jeon Hye Ji, Park Jin-Seong
School of Electrical and Electronic Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea.
ACS Appl Mater Interfaces. 2014 Jun 25;6(12):9228-35. doi: 10.1021/am5013672. Epub 2014 Jun 12.
This paper addressed the effect of gallium nitrate hydrate addition on thin film transistor (TFT) performance and positive bias stability of amorphous zinc tin oxide (ZTO) TFTs by solution processing, Further, the mechanisms responsible for chemical properties and electronic band structure are explored. A broad exothermic peak accompanied by weight loss appeared in the range from about 350 to 570 °C for the ZTO solution; the thermal reaction of the Ga-ZTO:N solution was completed at 520 °C. This is because the gallium nitrate hydrate precursor promoted the decomposition and dehydroxylation reaction for Zn(CH3COO)2·2H2O and/or SnCl2·2H2O precursors. The concentrations of carbon and chloride in gallium nitrate hydrate added ZTO films annealed at 400 °C have a lower value (C 0.65, Cl 0.65 at. %) compared with those of ZTO films (C 3.15, Cl 0.82 at. %). Absorption bands at 416, 1550, and 1350 cm(-1) for GaZTO:N films indicated the presence of ZnGa2O4, N-H, and N═O groups by Fourier transform infrared spectroscopy measurement, respectively. As a result, an inverted staggered Ga-ZTO:N TFT exhibited a mobility of 4.84 cm(2) V(-1) s(-1) in the saturation region, a subthreshold swing of 0.35 V/decade, and a threshold gate voltage (Vth) of 0.04 V. In addition, the instability of Vth values of the ZTO TFTs under positive bias stress conditions was suppressed by adding Ga and N from 13.6 to 3.17 V, which caused a reduction in the oxygen-related defects located near the conduction band.
本文通过溶液工艺研究了添加水合硝酸镓对非晶态锌锡氧化物（ZTO）薄膜晶体管（TFT）性能及正偏压稳定性的影响。此外，还探究了其化学性质和电子能带结构的相关机制。ZTO溶液在约350至570℃范围内出现了一个伴随失重的宽放热峰；Ga-ZTO:N溶液的热反应在520℃时完成。这是因为水合硝酸镓前驱体促进了Zn(CH3COO)2·2H2O和/或SnCl2·2H2O前驱体的分解和脱羟基反应。与ZTO薄膜（C 3.15，Cl 0.82 at.%）相比，在400℃退火的添加水合硝酸镓的ZTO薄膜中碳和氯的浓度较低（C 0.65，Cl 0.65 at.%）。通过傅里叶变换红外光谱测量，GaZTO:N薄膜在416、1550和1350 cm(-1)处的吸收带分别表明存在ZnGa2O4、N-H和N═O基团。结果，一个反向交错的Ga-ZTO:N TFT在饱和区的迁移率为4.84 cm(2) V(-1) s(-1)，亚阈值摆幅为0.35 V/十倍频程，阈值栅极电压（Vth）为0.04 V。此外，通过添加Ga和N，ZTO TFT在正偏压应力条件下Vth值的不稳定性从13.6 V降低到3.17 V，这导致导带附近与氧相关的缺陷减少。
