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Low temperature processed complementary metal oxide semiconductor (CMOS) device by oxidation effect from capping layer.

Wang Z, Al-Jawhari HA, Nayak PK, Caraveo-Frescas JA, Wei N, Hedhili MN, Alshareef HN - Sci Rep (2015)

Bottom Line: The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase.The oxidation process can be realized by annealing at temperature as low as 190 °C in air, which is significantly lower than the temperature generally required to form tin dioxide.Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

View Article: PubMed Central - PubMed

Affiliation: Materials Science and Engineering, King Abdullah University of Science &Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.

ABSTRACT
In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190 °C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

No MeSH data available.


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Materials characterizations for TFT channel layers.XPS Sn 4d peaks of (a) before and (b) after annealing bilayer sample; (c) XPS Cu 2p peaks of bilayer sample. (d) Raman spectra of before and after annealing bilayer samples and SnO single layer sample.
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f4: Materials characterizations for TFT channel layers.XPS Sn 4d peaks of (a) before and (b) after annealing bilayer sample; (c) XPS Cu 2p peaks of bilayer sample. (d) Raman spectra of before and after annealing bilayer samples and SnO single layer sample.

Mentions: Recently, we have demonstrated a detailed investigation of the origin of p-type transport behavior in SnO channel TFTs10. Here we focus on the origin of n-type transport behavior in Cu2O/SnO bilayer TFTs. To investigate the oxidation state of tin in Cu2O/SnO bilayer, X-ray photoelectron spectroscopy (XPS) was performed on the before annealing (BA) and after annealing (AA) bilayer samples, which were prepared under the same conditions used in the TFTs fabrication (i.e., annealing was performed at 190°C for 30 min in air). The XPS spectra of the Sn 4d peaks of BA and AA samples are presented in Figure 4(a) and (b), respectively. It is reported that the Sn 4d peak is a doublet and consists of Sn 4d3/2 and Sn 4d5/2 located at binding energy of 27.3 and 26.2 eV, respectively2425. The deconvolution of both Sn 4d peaks of BA and AA samples show Sn 4d3/2 and Sn 4d5/2 doublet peaks, with a chemical shift of ~0.7 eV between doublet peaks, which is consistent with the report from Themlin et al.26 For Sn4+, Sn 4d3/2 and Sn 4d5/2 peaks are located at 27.4 and 26.3 eV, respectively; in contrast, for Sn2+, Sn 4d3/2 and Sn 4d5/2 peaks are located at 26.7 and 25.6 eV, respectively. This is a clear evidence of the co-existance of both SnO and SnO2 phases in our bilayers. In case of both BA and AA samples, Sn 4d peak corresponding to metallic tin could be observed, this is nature of direct current (dc) reactive magnetron sputtering thin film and is consistent with our previous report10. Interestingly, the atomic content (in at%) of Sn4+, Sn2+ and Sn0 are determined to be 28, 62 and 10%, respectively in BA sample, and 78, 16 and 6%, respectively in AA sample. In the BA sample, the dominant phase is determined to be SnO. However, the content of n-type SnO2 phase significantly increases in AA sample, and becomes dominant (~78 at%) after the PDA process, which we believe is the origin of n-type transport behavior in the bilayer TFTs. The analysis result of XPS Sn 3d spectra of BA and AA sample is in agreement of XPS Sn 4d spectra (Figure S5).


Low temperature processed complementary metal oxide semiconductor (CMOS) device by oxidation effect from capping layer.

Wang Z, Al-Jawhari HA, Nayak PK, Caraveo-Frescas JA, Wei N, Hedhili MN, Alshareef HN - Sci Rep (2015)

Materials characterizations for TFT channel layers.XPS Sn 4d peaks of (a) before and (b) after annealing bilayer sample; (c) XPS Cu 2p peaks of bilayer sample. (d) Raman spectra of before and after annealing bilayer samples and SnO single layer sample.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f4: Materials characterizations for TFT channel layers.XPS Sn 4d peaks of (a) before and (b) after annealing bilayer sample; (c) XPS Cu 2p peaks of bilayer sample. (d) Raman spectra of before and after annealing bilayer samples and SnO single layer sample.
Mentions: Recently, we have demonstrated a detailed investigation of the origin of p-type transport behavior in SnO channel TFTs10. Here we focus on the origin of n-type transport behavior in Cu2O/SnO bilayer TFTs. To investigate the oxidation state of tin in Cu2O/SnO bilayer, X-ray photoelectron spectroscopy (XPS) was performed on the before annealing (BA) and after annealing (AA) bilayer samples, which were prepared under the same conditions used in the TFTs fabrication (i.e., annealing was performed at 190°C for 30 min in air). The XPS spectra of the Sn 4d peaks of BA and AA samples are presented in Figure 4(a) and (b), respectively. It is reported that the Sn 4d peak is a doublet and consists of Sn 4d3/2 and Sn 4d5/2 located at binding energy of 27.3 and 26.2 eV, respectively2425. The deconvolution of both Sn 4d peaks of BA and AA samples show Sn 4d3/2 and Sn 4d5/2 doublet peaks, with a chemical shift of ~0.7 eV between doublet peaks, which is consistent with the report from Themlin et al.26 For Sn4+, Sn 4d3/2 and Sn 4d5/2 peaks are located at 27.4 and 26.3 eV, respectively; in contrast, for Sn2+, Sn 4d3/2 and Sn 4d5/2 peaks are located at 26.7 and 25.6 eV, respectively. This is a clear evidence of the co-existance of both SnO and SnO2 phases in our bilayers. In case of both BA and AA samples, Sn 4d peak corresponding to metallic tin could be observed, this is nature of direct current (dc) reactive magnetron sputtering thin film and is consistent with our previous report10. Interestingly, the atomic content (in at%) of Sn4+, Sn2+ and Sn0 are determined to be 28, 62 and 10%, respectively in BA sample, and 78, 16 and 6%, respectively in AA sample. In the BA sample, the dominant phase is determined to be SnO. However, the content of n-type SnO2 phase significantly increases in AA sample, and becomes dominant (~78 at%) after the PDA process, which we believe is the origin of n-type transport behavior in the bilayer TFTs. The analysis result of XPS Sn 3d spectra of BA and AA sample is in agreement of XPS Sn 4d spectra (Figure S5).

Bottom Line: The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase.The oxidation process can be realized by annealing at temperature as low as 190 °C in air, which is significantly lower than the temperature generally required to form tin dioxide.Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

View Article: PubMed Central - PubMed

Affiliation: Materials Science and Engineering, King Abdullah University of Science &Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.

ABSTRACT
In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190 °C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

No MeSH data available.


Related in: MedlinePlus