a-IGZO中H的影响 肖祥 2015.12.25

ZnO Oxygen vacancy? Zn interstitial? H ?

PLD a-IGZO中的高浓度H RBS/HSF SIMS 两种不同的分析方法（SIMS，RBS/HSF）证明 ～2-4×1020 cm-3 H in PLD a-IGZO K. Nomura, T. Kamiya, and H. Hosono, “Effects of Diffusion of Hydrogen and Oxygen on Electrical Properties of Amorphous Oxide Semiconductor, In-Ga-Zn-O,” ECS J. Solid State Science and Technology, 2(1) P5-P8 (2013).

a-IGZO中的H的存在形式 FTIR Raman FTIR在～3270 cm-1 中无尖锐的吸收峰，排除H2O的存在 Raman在～4160 cm-1 处无Raman shift，排除H2的存在 H以-OH形式存在于a-IGZO中 K. Nomura, T. Kamiya, and H. Hosono, “Effects of Diffusion of Hydrogen and Oxygen on Electrical Properties of Amorphous Oxide Semiconductor, In-Ga-Zn-O,” ECS J. Solid State Science and Technology, 2(1) P5-P8 (2013).

a-IGZO中的H的存在形式 -OH Stable H与金属原子配位数为3的氧原子结合，形成最稳定的结构。 K. Nomura, T. Kamiya, H. Hosono, “Subgap states, doping and defect formation energies in amorphous oxide semiconductor a-InGaZnO4 studied by density functional theory,” Phys. Status Solid A 207, No. 7, 1698-1703 (2010).

a-IGZO中的H的作用 Hydrogen以-O2-H+存在，由过量的O补偿，所以即使有高浓度的H，Ne也在10-15cm-3。 Y. K. Ide, T. Kamiya, and H. Hosono et al., “Effects of excess oxygen on operation characteristics of amorphous In-Ga-Zn-O thin-film transistors,”Appl. Phys. Lett. 99, 093507(2011).

a-IGZO中的H的作用 充当施主 H2 plasma处理和H2退火，器件全开。（H作为浅施主） Unannealed a-IGZO films deposited at RT contains impurity hydrogens at the density of 1020–21 cm3,10 and some hydrogens are considered to passivate electron traps. Dry O2 annealing at 300 C oxidizes a-IGZO layers and reduces oxygen-deficiency-related defects as reported in Ref. 6, where enough portion of the hydrogens still remains to passivate traps. Annealing at 400 C would have a more efficient effect for oxidation, but removes the hydrogens forming the passivated bonds, leading to a de-passivation effect and the deteriorated TFT characteristics. Additional wet O2 annealing re-introduces hydrogens and passivates the newly created electron traps and recovers the TFT characteristics similar to those of the best, 300 C-annealed TFT. H2 plasma处理和H2退火，器件全开。（H作为浅施主） Y. Hanyu, H. Hosono, and T. Kamiya et al., “Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors,” Appl. Phys. Lett. 103, 202114(2013).

钝化电子陷阱（electron traps） a-IGZO中的H的作用 钝化电子陷阱（electron traps） Dry O2 annealing Dry O2 annealing在250℃～300℃条件下得到最好的器件性能。 Dry O2 annealing在400℃及以上器件性能退化明显。 400℃以上H2O的解吸附完成， 猜测上述的400℃及以上的dry O2 annealing器件性能退化与H2O的完全解吸附有关。 Hydrogen的耗尽导致电子陷阱态的产生，器件性能退化。 Y. Hanyu, H. Hosono, and T. Kamiya et al., “Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors,” Appl. Phys. Lett. 103, 202114(2013).

钝化电子陷阱（electron traps） a-IGZO中的H的作用 钝化电子陷阱（electron traps） Recovery Re-doped Hydrogen’ desorption Unannealed a-IGZO films deposited at RT contains impurity hydrogens at the density of 1020–21 cm3,10 and some hydrogens are considered to passivate electron traps. Dry O2 annealing at 300 C oxidizes a-IGZO layers and reduces oxygen-deficiency-related defects as reported in Ref. 6, where enough portion of the hydrogens still remains to passivate traps. Annealing at 400 C would have a more efficient effect for oxidation, but removes the hydrogens forming the passivated bonds, leading to a de-passivation effect and the deteriorated TFT characteristics. Additional wet O2 annealing re-introduces hydrogens and passivates the newly created electron traps and recovers the TFT characteristics similar to those of the best, 300 C-annealed TFT. H2 plasma处理和H2退火，器件全开。（H作为浅施主） 400℃wet O2 anneling后，器件特性恢复。 Y. Hanyu, H. Hosono, and T. Kamiya et al., “Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors,” Appl. Phys. Lett. 103, 202114(2013).

钝化电子陷阱（electron traps） a-IGZO中H的作用 钝化电子陷阱（electron traps） Wet annealing VS dry annealing Dry annealing: 400 °C, 1h, dry O2, 1 atm. Wet annealing: 400 °C, 1h, wet O2 gases with H2O partial pressure ratios (RH2O). Dry annealing可以改善器件电学性能（μ，SS, hysteresis）; Wet annealing在RH2O为7.3%和19.7%时可以改善μ，SS, hysteresis，效果比dry O2好，证明wet anneling能更加有效的降低靠近CBM的电子陷阱；但是，继续增加RH2O会导致SS增加。 K. Nomura, T. Kamiya, H. Hosono et al., “Defect passivation and homogenization of amorphous oxide thin-film transistor by wet O2 annealing,” Appl. Phys. Lett., 93, 192107 (2008).

钝化电子陷阱（electron traps） a-IGZO中的H的作用 钝化电子陷阱（electron traps） Wet annealing VS dry annealing 刚淀积的a-IGZO中含有大量的H2-和H2O-related species。 H2O-related molecules的解吸附会产生oxygen-deficiencis向沟道提供电子。 低于310℃退火过程中会产生oxygen deficiencies相关的缺陷态，导致电导率的增大。 更高温度N2中退火并不能降低缺陷态密度，电阻率会一直上升，并且cooling down过程中不会出现电导率的恢复；而O2和H2O中退火在更高温度下可以降低缺陷态密度(重新氧化)，电导率下降，然而cooling down到室温电阻率会恢复。 Wet annealing可以抑制H2O, O2和Zn的解吸附，所以带来更有效的器件性能改善。 K. Nomura, T. Kamiya, H. Hosono et al., “Defect passivation and homogenization of amorphous oxide thin-film transistor by wet O2 annealing,” Appl. Phys. Lett., 93, 192107 (2008). T. Kamiya and H. Hosono, “Roles of Hydrogen in Amorphous Oxide Semiconductor” ECS Transaction, 54 (1) 103-113 (2013).

在as-deposited的a-IGZO中存在~1021cm-3的高浓度Hydrogen。 H以-OH的形式存在于a-IGZO中。 -OH可以充当donor，但是会被过量O补偿。同时-OH可以钝化a-IGZO中oxygen-deficiencies related的electron traps(靠近CBM?)。 高温（＞400℃）dry O2退火H2O解吸附会导致-OH的钝化作用减弱，器件性能退化。Wet annealing可以抑制H2O的解吸附，同时也可以在H2O解吸附后重新掺杂H，恢复器件性能。

磁控溅射a-IGZO中H的来源 a-IGZO靶材中的H？（H含量与淀积速率无关） 放置环境中的H?（H含量与放置时间有关）

磁控溅射a-IGZO中H的来源 腔体残余H和靶材表面吸附H成为a-IGZO薄膜中H的主要来源。 UHV （～10-7 Pa）sputtering的a-IGZO薄膜中的H含量在5×19cm-3，远低于常规(～10-4 Pa，STD)溅射的a-IGZO(5×1020cm-3)。 H的含量与淀积速率相关，排除a-IGZO靶材中的H，由腔体中残余H有关。 H含量与放置时间无关，排除环境中H的扩散。 H含量与预溅射功率有关，说明H与靶材表面的吸附H有关。 腔体残余H和靶材表面吸附H成为a-IGZO薄膜中H的主要来源。 T. Miyase, H. Hosono, and T. Kamiya et al., “Roles of Hydrogen in Amorphous Oxide Semiconducyor In-Ga-Zn-O: Comparison of Conventional and Ultra-High-Vacuum Sputtering,” ECS Journal of Solid State Science and Technology, 3 (9) Q3085-Q3090 (2014).

磁控溅射a-IGZO中的H的作用 STD sputtering的a-IGZO薄膜的H2、H2O、O2、In、Zn、Ga的TDS解吸附明显。（由STD a-IGZO中高含量的H引起） T. Miyase, H. Hosono, and T. Kamiya et al., “Roles of Hydrogen in Amorphous Oxide Semiconducyor In-Ga-Zn-O: Comparison of Conventional and Ultra-High-Vacuum Sputtering,” ECS Journal of Solid State Science and Technology, 3 (9) Q3085-Q3090 (2014).

磁控溅射a-IGZO中H对薄膜的影响 UHV：In:Ga:Zn=1:1.1:1.0 STD: In:Ga:Zn=1:0.9:0.6 STD a-IGZO薄膜中大量的-OH导致金属（特别是Zn）的解吸附加剧，所以STD a-IGZO中的组分差异较大。 T. Miyase, H. Hosono, and T. Kamiya et al., “Roles of Hydrogen in Amorphous Oxide Semiconducyor In-Ga-Zn-O: Comparison of Conventional and Ultra-High-Vacuum Sputtering,” ECS Journal of Solid State Science and Technology, 3 (9) Q3085-Q3090 (2014).

磁控溅射a-IGZO中H对薄膜的影响 含H少的UHV a-IGZO薄膜的结构致密性差。 T. Miyase, H. Hosono, and T. Kamiya et al., “Roles of Hydrogen in Amorphous Oxide Semiconducyor In-Ga-Zn-O: Comparison of Conventional and Ultra-High-Vacuum Sputtering,” ECS Journal of Solid State Science and Technology, 3 (9) Q3085-Q3090 (2014).

UHV薄膜中H少，对深能态的electron traps的钝化作用差。 STD a-IGZO TFT退火前后都呈现良好的开关特性。 UHV a-IGZO TFT退火前处于常关状态，只有退火有才会出现开关特性。 UHV薄膜中H少，对深能态的electron traps的钝化作用差。 T. Miyase, H. Hosono, and T. Kamiya et al., “Roles of Hydrogen in Amorphous Oxide Semiconducyor In-Ga-Zn-O: Comparison of Conventional and Ultra-High-Vacuum Sputtering,” ECS Journal of Solid State Science and Technology, 3 (9) Q3085-Q3090 (2014).

UHV a-IGZO TFT的PBS下阈值电压的漂移量大于STD a-IGZO TFT。 T. Miyase, H. Hosono, and T. Kamiya et al., “Roles of Hydrogen in Amorphous Oxide Semiconducyor In-Ga-Zn-O: Comparison of Conventional and Ultra-High-Vacuum Sputtering,” ECS Journal of Solid State Science and Technology, 3 (9) Q3085-Q3090 (2014).

谢谢！