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991.
R. Jangir Tapas GanguliPragya Tiwari S. PorwalHimanshu Srivastava S.K. RaiB.Q. Khattak S.M. Oak 《Applied Surface Science》2011,257(22):9323-9328
β-Ga2O3 nanostructures including nanowires, nanoribbons and nanosheets were synthesized via thermal annealing of gold coated GaAs substrates in N2 ambient. GaAs substrates with different dopants were taken as the starting material to study the effect of doping on the growth and photoluminescence properties of β-Ga2O3 nanostructures. The nanostructures were investigated by Grazing Incident X-ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Energy Dispersive X-ray Spectroscopy, room temperature photoluminescence and optical absorbance. The selected area electron diffraction and High resolution-TEM observations suggest that both nanowires and nanobelts are single crystalline. Different growth directions were observed for nanowires and nanoribbons, indicating the different growth patterns of these nanostructures. The PL spectra of β-Ga2O3 nanostructures exhibit a strong UV-blue emission band centered at 410 nm, 415 nm and 450 nm for differently doped GaAs substrates respectively. A weak red luminescence peak at 710 nm was also observed in all the samples. The optical absorbance spectrum showed intense absorption features in the UV spectral region. The growth and luminescence mechanism in β-Ga2O3 nanostructures are also discussed. 相似文献
992.
V.M. Mikoushkin 《Applied Surface Science》2011,257(11):4941-4944
Nitridation of GaAs (1 0 0) by N2+ ions with energy Ei = 2500 eV has been studied by Auger- and Electron Energy Loss Spectroscopy under experimental conditions, when electrons ejected only by nitrated layer, without contribution of GaAs substrate, were collected. Diagnostics for quantitative chemical analysis of the nitrated layers has been developed using the values of NKVV Auger energies in GaN and GaAsN chemical phases measured in one experiment, with the accuracy being sufficient for separating their contributions into the experimental spectrum. The conducted analysis has shown that nanofilm with the thickness of about 4 nm was fabricated, consisting mainly of dilute alloy GaAs1−xNx with high concentration of nitrogen x ∼ 0.09, although the major part of the implanted nitrogen atoms are contained in GaN inclusions. It was assumed that secondary ion cascades generated by implanted ions play an important role in forming nitrogen-rich alloy. 相似文献
993.
ZnO buffer layers were deposited on n-Si (1 0 0) substrate by rf magnetron sputtering at a lower power of 40 W. Then Ag-doped ZnO (SZO) films were deposited on buffered and non-buffered Si at a higher sputtering power of 100 W. The effects of buffer layer on the structural, electrical and optical properties of SZO films were investigated. The three-dimensional island growth process of ZnO buffer layer was discussed. The energy band diagram of p-SZO/n-Si heterojunction was constructed based on Anderson's model. Results show the ZnO buffer layer leads to better properties of SZO film, including larger grain size, smoother surface, higher carrier mobility, better rectifying behavior, lower interface state density, and weaker deep-level emission. It is because the ZnO buffer layer effectively relaxes the partial stress induced by the large lattice mismatch between SZO and Si. 相似文献
994.
Xiao GuoHao Yu Yu-Long Jiang Guo-Ping RuDavid Wei Zhang Bing-Zong Li 《Applied Surface Science》2011,257(24):10571-10575
Nickel silicide formation on Si(1 1 0) and Si(1 0 0) substrate was investigated in this paper. It is confirmed that nickel monosilicide (NiSi) starts to form after 450 °C annealing for Si(1 0 0) substrate, but a higher annealing temperature is required for NiSi formation on Si(1 1 0) substrate, which is demonstrated by X-ray diffraction (XRD) and Raman scattering spectroscopy. The higher formation temperature of NiSi is attributed to the larger Ni2Si grain size formed on Si(1 1 0) substrate. Ni silicided Schottky contacts on both Si(1 0 0) and Si(1 1 0) substrates were also fabricated for electrical characteristics evaluation. It clearly reveals that the rectifying characteristics of NiSi/n-Si(1 1 0) Schottky contacts is inferior to that of NiSi/n-Si(1 0 0) Schottky contacts, which is attributed to a lower Schottky barrier height and a rougher contact interface. The formation kinetics for nickel silicide on Si(1 1 0) substrate is also discussed in this paper. 相似文献
995.
Ningli AnHongzhong Liu Yucheng DingMin Zhang Yiping Tang 《Applied Surface Science》2011,257(9):3831-3835
In the present study, poly(vinylidene fluoride) (PVDF)/nano-TiO2 electroactive film was prepared by coating a substrate with an acetone/DMF solution, which was evaporated at a high temperature (110 °C). The crystallisation behaviour, dynamic mechanical properties and electroactive properties of this PVDF/nano-TiO2 electroactive film were investigated. The cross-section and surface of the film were observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) results showed that the film containing the PVDF β phase, the desired ferroelectric phase, was obtained by crystallising the mixed solution of nano-TiO2 and PVDF at 110 °C, while the film containing the α phase was obtained from the crystallisation of the pure PVDF solution at the same temperature. It was found that the storage modulus, the room-temperature dielectric constant and the electric breakdown strength of the composite films were much higher than those of a pure PVDF film. TiO2 improved the mechanical properties and electroactive properties of the film. The results indicate that PVDF/nano-TiO2 composite films can be applied to the fabrication of self-sensing actuator devices. 相似文献
996.
B. HuB.Y. Man C. YangM. Liu C.S. ChenX.G. Gao S.C. XuC.C. Wang Z.C. Sun 《Applied Surface Science》2011,258(1):525-529
Mn-doped GaN films (Ga1−xMnxN) were grown on sapphire (0 0 0 1) using Laser assisted Molecular Beam Epitaxy (LMBE). High-quality nanocrystalline Ga1−xMnxN films with different Mn concentration were then obtained by thermal annealing treatment for 30 min in the ammonia atmosphere. Mn ions were incorporated into the wurtzite structure of the host lattice by substituting the Ga sites with Mn3+ due to the thermal treatment. Mn3+, which is confirmed by XPS analysis, is believed to be the decisive factor in the origin of room-temperature ferromagnetism. The better room-temperature ferromagnetism is given with the higher Mn3+ concentration. The bound magnetic polarons (BMP) theory can be used to prove our room-temperature ferromagnetic properties. The film with the maximum concentration of Mn3+ presents strongest ferromagnetic signal at annealing temperature 950 °C. Higher annealing temperature (such as 1150 °C) is not proper because of the second phase MnxGay formation. 相似文献
997.
Jie XiaoN. Lozova Ya.B. Losovyj D. WootenI. Ketsman M.W. SwinneyJ. Petrosky J. McCloryYa.V. Burak V.T. AdamivA.T. Brant P.A. Dowben 《Applied Surface Science》2011,257(8):3399-3403
We have compared the photovoltaic charging of the (1 0 0) surface termination for Cu doped and undoped Li2B4O7. While the surface charging at the (1 0 0) surface of Li2B4O7 is significantly greater than observed at (1 1 0) surface, the Cu doping plays a role in reducing the surface photovoltage effects. With Cu doping of Li2B4O7, the surface photovoltaic charging is much diminished at the (1 0 0) surface. The density of states observed with combined photoemission and inverse photoemission remains similar to that observed for the undoped material, except in the vicinity of the conduction band edge. 相似文献
998.
Duy-Thach PhanGwiy-Sang Chung 《Applied Surface Science》2011,257(9):4339-4343
Zinc oxide (ZnO) thin films were deposited on unheated silicon substrates via radio frequency (RF) magnetron sputtering, and the post-deposition annealing of the ZnO thin films was performed at 400 °C, 600 °C, 800 °C, and 1000 °C. The characteristics of the thin films were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The films were then used to fabricate surface acoustic wave (SAW) resonators. The effects of post-annealing on the SAW devices are discussed in this work. Resulting in the 600 °C is determined as optimal annealing temperature for SAW devices. At 400 °C, the microvoids exit between the grains yield large root mean square (RMS) surface roughness and higher insertion losses in SAW devices. The highest RMS surface roughness, crack and residual stress cause a reduction of surface velocity (about 40 m/s) and increase dramatically insertion loss at 1000 °C. The SAW devices response becomes very weak at this temperature, the electromechanical coupling coefficient (k2) of ZnO film decrease from 3.8% at 600 °C to 1.49% at 1000 °C. 相似文献
999.
1000.