The incubation layer with amorphous structure between the substrate and crystalline layer may obviously affect the performance for a microcrystalline Si thin film transistor (μc-Si TFT),especially for the bottom gate...The incubation layer with amorphous structure between the substrate and crystalline layer may obviously affect the performance for a microcrystalline Si thin film transistor (μc-Si TFT),especially for the bottom gate TFT(BG-TFT).It is found that decreasing the ratio of SiH 4/(H 2+SiH 4) is an effective way to decrease the incubation layer thickness of μc-Si directly deposited by VHF PECVD without any further thermal or laser treatment.Based on the μc-Si with a thin incubation layer,the BG-TFT with Al/SiN x/μc-Si/n+-μc-Si/Al structure is fabricated.The ratio of on-state current to off-state current is up to 106,the mobility is around 0.7cm2/(V·s),and the threshold voltage is about 5V.展开更多
Deposition of clean and defect-free atomically thin two-dimensional crystalline flakes on surfaces by mechanical exfoliation of layered bulk materials has proven to be a powerful technique, but it requires a fast, rel...Deposition of clean and defect-free atomically thin two-dimensional crystalline flakes on surfaces by mechanical exfoliation of layered bulk materials has proven to be a powerful technique, but it requires a fast, reliable and non-destructive way to identify the atomically thin flakes among a crowd of thick flakes. In this work, we provide general guidelines to identify ultrathin flakes of TaSe2 by means of optical microscopy and Raman spectroscopy. Additionally, we determine the optimal substrates to facilitate the optical identification of atomically thin TaSe2 crystals. Experimental realization and isolation of ultrathin layers of TaSe2 enables future studies on the role of the dimensionality in interesting phenomena such as superconductivity and charge density waves.展开更多
In this work, the influence of crystal structure on the friction coefficient of zinc oxide （ZnO） films was studied. The ZnO films were deposited on a Si （100） substrate using an atomic layer deposition process, an...In this work, the influence of crystal structure on the friction coefficient of zinc oxide （ZnO） films was studied. The ZnO films were deposited on a Si （100） substrate using an atomic layer deposition process, and the crystal structure of the ZnO films was changed by adjusting the substrate temperature. The surface morphology and the crystal structure of the ZnO films were meas- ured by an atomic force microscope and an X-ray diffractometer, respectively, and the friction coefficient of the ZnO fi）ms was measured by a ball-on-disk dry sliding tester. The results show that the ZnO films deposited at substrate temperatures below 200~C are dominated by （100）, （002） and （101）-orientated crystals, while the ZnO films deposited at substrate temperatures above 250~C are dominated by （002）-orientated crystals, and that the crystal structure influences the friction coefficient of ZnO films greatly. The ZnO films with （002）-orientated crystals possess a larger friction coefficient than those with other orientated crystals. In order to verify this conclusion, we measured the friction behavior of the ZnO single crystals with different orienta- tions. The results are consistent well with our conclusion.展开更多
文摘The incubation layer with amorphous structure between the substrate and crystalline layer may obviously affect the performance for a microcrystalline Si thin film transistor (μc-Si TFT),especially for the bottom gate TFT(BG-TFT).It is found that decreasing the ratio of SiH 4/(H 2+SiH 4) is an effective way to decrease the incubation layer thickness of μc-Si directly deposited by VHF PECVD without any further thermal or laser treatment.Based on the μc-Si with a thin incubation layer,the BG-TFT with Al/SiN x/μc-Si/n+-μc-Si/Al structure is fabricated.The ratio of on-state current to off-state current is up to 106,the mobility is around 0.7cm2/(V·s),and the threshold voltage is about 5V.
文摘Deposition of clean and defect-free atomically thin two-dimensional crystalline flakes on surfaces by mechanical exfoliation of layered bulk materials has proven to be a powerful technique, but it requires a fast, reliable and non-destructive way to identify the atomically thin flakes among a crowd of thick flakes. In this work, we provide general guidelines to identify ultrathin flakes of TaSe2 by means of optical microscopy and Raman spectroscopy. Additionally, we determine the optimal substrates to facilitate the optical identification of atomically thin TaSe2 crystals. Experimental realization and isolation of ultrathin layers of TaSe2 enables future studies on the role of the dimensionality in interesting phenomena such as superconductivity and charge density waves.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.50825501)the Science Fund for Creative Research Groups(Grant No.51321092)+1 种基金the National Natural Science Foundation of China(Grant Nos.51335005 and 91323302)the National Science and Technology Major Project(Grant No.2008ZX02104-001)
文摘In this work, the influence of crystal structure on the friction coefficient of zinc oxide （ZnO） films was studied. The ZnO films were deposited on a Si （100） substrate using an atomic layer deposition process, and the crystal structure of the ZnO films was changed by adjusting the substrate temperature. The surface morphology and the crystal structure of the ZnO films were meas- ured by an atomic force microscope and an X-ray diffractometer, respectively, and the friction coefficient of the ZnO fi）ms was measured by a ball-on-disk dry sliding tester. The results show that the ZnO films deposited at substrate temperatures below 200~C are dominated by （100）, （002） and （101）-orientated crystals, while the ZnO films deposited at substrate temperatures above 250~C are dominated by （002）-orientated crystals, and that the crystal structure influences the friction coefficient of ZnO films greatly. The ZnO films with （002）-orientated crystals possess a larger friction coefficient than those with other orientated crystals. In order to verify this conclusion, we measured the friction behavior of the ZnO single crystals with different orienta- tions. The results are consistent well with our conclusion.
