Influence of rapid-thermal-annealing temperature on properties of rf-sputtered SnOx thin films

An extremely sensitive dependence of the electronic properties of SnOx film on sputtering deposition power is discovered experimentally. The carrier transport sharply switches from n-type to p-type when the sputtering power increases by less than 2%. The best n-type carrier transport behavior is observed in thin-film transistors (TFTs) produced at a sputtering power just below a critical value (120 W). In contrast, at just above the critical sputtering power, the p-type behavior is found to be the best with the TFTs showing the highest on/off ratio of 1.79 × 104 and the best subthreshold swing among all the sputtering powers that we have tested. A further increase in the sputtering power by only a few percent results in a drastic drop in on/off ratio by more than one order of magnitude. Scanning electron micrographs, x-ray diffraction spectra, x-ray photoelectron spectroscopy, as well as TFT output and transfer characteristics are analyzed. Our studies suggest that the sputtering power critically affects the stoichiometry of the SnOx film.

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“…Furthermore, some cracks were observed in annealed film sputtered at 150 W (Fig. 4(d)) which could be related to grain boundaries25.…”

Section: Resultsmentioning

confidence: 96%

“…To the best of our knowledge, the only reported flexible SnO TFT was fabricated through DC magnetron sputtering19. Effects of different oxygen partial pressures during sputtering and post-annealing in different gas/vacuum environments have also been studied19212526.…”

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confidence: 99%

Extremely Sensitive Dependence of SnOx Film Properties on Sputtering Power

Liu

Xin

et al. 2016

Sci Rep

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“…24,44,47 During the annealing treatment in ambient air, oxygen molecules from the environment are adsorbed onto the surface of the SnO thin film due to the presence of additional heat energy and obtain higher surface diffusion, thereby causing lattice relaxation and increased crystallization. 60,61 Unfortunately, the increase in crystallization is followed by an increase in the intermediate phase. The two sub-stoichiometric SnO x (1 < x < 2) phases lying between the A 1g and B 1g modes are promoted when more oxygen is introduced into the SnO layer.…”

Section: Resultsmentioning

confidence: 99%

Room-Temperature Fabrication of p-Type SnO Semiconductors Using Ion-Beam-Assisted Deposition

Januar

Prakoso

Zhong

et al. 2022

ACS Appl. Mater. Interfaces

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Over the past decade, SnO has been considered a promising p-type oxide semiconductor. However, achieving high mobility in the fabrication of p-type SnO films is still highly dependent on the post-annealing procedure, which is often used to make SnO, due to its metastable nature, readily convertible to SnO2 and/or intermediate phases. This paper demonstrates a fully room-temperature fabrication of p-type SnO x thin films using ion-beam-assisted deposition. This technique offers independent control between ion density, via the ion-gun anode current and oxygen flow rate, and ion energy, via the ion-gun anode voltage, thus being able to optimize the optical band gap and the hole mobility of the SnO films to reach 2.70 eV and 7.89 cm2 V–1 s–1, respectively, without the need for annealing. Remarkably, this is the highest mobility reported for p-type SnO films whose fabrication was carried out entirely at room temperature. Using first-principles calculations, we rationalize that the high mobility is associated with the fine-tuning of the Sn-rich-related defects and lattice densification, obtained by controlling the density and energy of the oxygen ions, both of which optimize the spatial overlap of the valence bands to form a continuous conduction path for the holes. Moreover, due to the absence of the annealing process, the Raman spectra reveal no significant signatures of microcrystal formation in the films. This behavior contrasts with the case involving the air-annealing procedure, where a complex interaction occurs between the formation of SnO microcrystals and the formation of SnO x intermediate phases. This interplay results in variations in grain texture within the film, leading to a lower optimum Hall mobility of only 5.17 cm2 V–1 s–1. Finally, we demonstrate the rectification characteristics of all-fabricated-at-room-temperature SnO x -based p–n devices to confirm the viability of the p-type SnO x films.

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“…Figure 2 b shows the XPS Sn 3 d 5/2 spectra of the deposited thin film. The XPS spectra were deconvoluted into three sub-peaks stemming from the oxidized states of Sn with 3 different oxidation numbers; here, the binding energies of the Sn 0 , Sn 2+ , and Sn 4+ components were 484.8, 486.0, and 486.7 eV, respectively [ 40 ]. Figure 2 c shows the relative peak area ratios of the Sn 0 , Sn 2+ , and Sn 4+ components calculated from the XPS spectra of the tin oxide thin film in Figure 2 b.…”

Section: Resultsmentioning

confidence: 99%

Floating Ni Capping for High-Mobility p-Channel SnO Thin-Film Transistors

et al. 2020

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We utilized Ni as a floating capping layer in p-channel SnO thin-film transistors (TFTs) to improve their electrical performances. By utilizing the Ni as a floating capping layer, the p-channel SnO TFT showed enhanced mobility as high as 10.5 cm2·V−1·s−1. The increase in mobility was more significant as the length of Ni capping layer increased and the thickness of SnO active layer decreased. The observed phenomenon was possibly attributed to the changed vertical electric field distribution and increased hole concentration in the SnO channel by the floating Ni capping layer. Our experimental results demonstrate that incorporating the floating Ni capping layer on the channel layer is an effective method for increasing the field-effect mobility in p-channel SnO TFTs.

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Influence of rapid-thermal-annealing temperature on properties of rf-sputtered SnOx thin films

Cited by 28 publications

References 43 publications

Extremely Sensitive Dependence of SnOx Film Properties on Sputtering Power

Extremely Sensitive Dependence of SnOx Film Properties on Sputtering Power

Room-Temperature Fabrication of p-Type SnO Semiconductors Using Ion-Beam-Assisted Deposition

Floating Ni Capping for High-Mobility p-Channel SnO Thin-Film Transistors

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