Metal Reaction-Induced Bulk-Doping Effect in Forming Conductive Source-Drain Regions of Self-Aligned Top-Gate Amorphous InGaZnO Thin-Film Transistors

Yang, Huan; Zhou, Xiaoliang; Fu, Haishi; Chang, Biao; Min, Yuxin; Peng, Hao; Lü, Lei; Zhang, Shengdong

doi:10.1021/acsami.0c21123

Cited by 38 publications

(31 citation statements)

References 43 publications

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“…3(c), no obvious difference is seen in Zn 2p signals. It is thus inferred that an oxidation-reduction reaction between Al and a-ZTO system takes place in the doping process, much similar to what happens in the Al, titanium (Ti) or manganese (Mn) reaction-doped a-IGZO [26,28,29] [26,28,29], forming oxygen vacancies and simultaneously leaving the displaced Sn interstitials that act as shallow donors. Thus, the oxidationreduction reaction could be described as…”

Section: Resultsmentioning

confidence: 76%

“…As shown, with Al reaction treatment, the area percentage of the red subpeak increases from 30 to 54%. The result suggests that large amounts of oxygen vacancies be generated during the Al reaction process [26][27][28]. Regarding the Sn 3d signals shown in Fig.…”

Section: Resultsmentioning

confidence: 87%

“…However, the plasma induced low resistance of AOS tends to be readily returned to the high-resistance state in subsequent post-annealing treatments in an oxidizing ambient [10,23,24]. Recently, it has been reported that the aluminum (Al) reaction is an effective and stable S/D doping method for fabrication of SATG a-IZO and a-IGZO TFTs [10,[23][24][25][26]. And, the Al reaction with a-ZTO films has also been investigated [27].…”

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confidence: 99%

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Self-Aligned Top-Gate Amorphous Zinc-Tin Oxide Thin-Film Transistor With Source/Drain Regions Doped by Al Reaction

Yang

Zhou

et al. 2021

IEEE J. Electron Devices Soc.

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A self-aligned fabrication process for top-gate amorphous zinc-tin oxide (a-ZTO) thin-film transistors (TFTs) is developed, in which the source/drain (S/D) doping is realized through depositing a thin aluminum (Al) film on S/D regions and performing a thermal annealing. Results indicate that a chemical oxidation-reduction reaction between Al and a-ZTO films takes place during the thermal annealing process, and shallow donors of oxygen vacancies and metal tin (Sn) interstitials are thus generated. The formed S/D regions have a high carrier concentration over 1 × 10 20 cm −3 , low sheet resistance of 0.57 kΩ/sq, and high thermal stability even in oxygen ambient. The fabricated a-ZTO TFTs exhibit excellent electrical performances, including a low channelwidth-normalized S/D resistance of about 7.05 Ω cm, a high fieldeffect mobility of 15.7 cm 2 /Vs, a high on/off current ratio of over 10 8 , and near-zero turn-on voltage. Moreover, good electrical stability with less than 0.2-V threshold voltage shift under ±30-V gate bias stresses is also achieved. Index Terms-Amorphous zinc-tin oxide, self-aligned top-gate, thin-film transistor, Al reaction doping, oxidation-reduction reaction. I. INTRODUCTIONMORPHOUS metal oxide semiconductors (AOS) thin-film transistors (TFTs) have been demonstrated to have relatively high carrier mobility, good performance uniformity over large-area, and low fabrication cost, and thereby regarded as one of the most promising devices applicable to advanced large area electronics and high-end integrated circuits [1][2][3][4][5][6][7][8][9]. The high mobility of AOS TFTs is usually attributed to the heavy metal cations, such as indium (In), which have an electronic configuration of (n-1)d 10 ns 0 (n ≥ 5) allowing largeradius spherical s orbitals and sufficient orbital overlapping [6][7][8]. As a result, the superiorities of the In-based AOS TFTs, like amorphous indium-gallium-zinc oxide (a-IGZO) [5-8] and amorphous indium-zinc oxide (a-IZO) [8][9][10][11] have earned them popularity in various applications. Unfortunately, In is toxic and short of reserve in earth [5,12,13]. On the other hand, the metal tin (Sn) is safe and abundant [12,13], and has the similar electronic configuration [8] and close coordination number [14] to indium in an amorphous oxide system. Thus, the In-free amorphous zinc-tin oxide (a-ZTO) has been investigated as a promising non-toxic low-cost AOS, and reasonably high This work was conducted in Shenzhen TFT and Advanced Display Lab and supported financially by NSFC under project 61774010, Shenzhen Municipal Scientific Program under Grants JCYJ20180504165449640, JCYJ20200109140610435, and XMHT20190201013.

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Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 87%

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confidence: 99%

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Self-Aligned Top-Gate Amorphous Zinc-Tin Oxide Thin-Film Transistor With Source/Drain Regions Doped by Al Reaction

Yang

Zhou

et al. 2021

IEEE J. Electron Devices Soc.

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“…The peaks located at 530.42 eV and 531.64 eV can be attributed to lattice oxygen (O L ) and oxygen vacancy (O V ), respectively. 2 The corresponding proportions between O L and O V are plotted in the inset. With the increase of deposition temperature, the ratio of O V /O L rises from 12.46% to 20.05% and then stabilizes at 21.96%, indicating that the higher in situ temperature benefits the formation of oxygen vacancy, consistent with the results of the U-V spectrophotometer.…”

Section: Structures and Properties Of Zto Thin Filmmentioning

confidence: 99%

“…Amorphous oxide semiconductors (AOS) are important electronic materials and have attracted considerable attention as the active layer of thin-film transistors (TFT) for advanced display applications due to the intrinsic advantages, such as low leakage current, high mobility, excellent large area uniformity and low manufacturing cost, compared with other candidates. 1,2 It has generally reached a consensus that only the heavy metal cations (HMC) with (n À 1)d 10 ns 0 (n Z4) electronic configuration can achieve high electron mobility even in an amorphous state due to the large overlaps of spherical s-orbits, which are insensitive to the direction. 3 Therefore, AOS materials composed of this HMC are aggressively investigated, especially since great progress has been achieved in amorphous IGZO (InGaZnO) TFT.…”

Section: Introductionmentioning

confidence: 99%