举例-蒸镀

摘 要
Zinc oxide thin films have been grown on (100)-oriented silicon substrate at a temperature of 100℃ by reactive e-beam evaporation. Structural, electrical and optical characteristics have been compared before and after annealing in air by measurements of X-ray diffraction, real and imaginary parts of the dielectric coefficient, refractive index and electrical resistivity. X-ray diffraction measurements have shown that ZnO films are highly c-axis-oriented with a full width at half maximum (FWMH) lower than 0.58. The electrical resistivity increases from 102 V cm to reach a value about 109 V cm after annealing at 750℃. The FWHM decreases after annealing treatment, which proves the crystal quality improvement. Ellipsometer measurements show the improvement of the refractive index and the real dielectric coefficient after annealing treatment at 750℃ of the ZnO films evaporated by electron beam. Atomic force microscopy shows that the surfaces of the electron beam evaporated ZnO are relatively smooth. Finally, a comparative study on structural and optical properties of the electron beamevaporated ZnO and the rf magnetron deposited one is discussed
2. Experimental
A VG V80H MBE system was used to fabricate all the ZnSSe thin films studied in this work. Commercial ITO-coated glass substrates were first cleaned using Decon 90 detergent and then rinsed in de-ionised water in an ultrasonic bath. After being baked dry at 100℃, they were loaded into the MBE system. Prior to the deposition, the substrates were preheated at 380℃ for a period of 20 min. The growth of ZnSSe thin films was carried out using a ZnS compound source and a Se elemental source. There are in total five samples used in this study. Samples 1 and 2 (group I) were grown with the same Se/ZnS flux ratio at substrate temperatures of 330℃ and 290℃, respectively. Samples 3–5 (group II) were grown under a higher (approximately twice) Se/ ZnS flux ratio at substrate temperatures of 310℃, 280℃ and 270℃, respectively. The as-grown thin films were cut into several pieces for various structural chara 电子束蒸发
Effect of annealing on the electrical and optical properties of electron beam evaporated ZnO thin films R. Al Asmar, G. Ferblantier, F. Mailly, P. Gall-Borrut, A. Foucaran* Centre d VElectronique et de Micro-optoe´lectronique de Montpellier, CEM2-UNIVERSITE MONTPELLIER II-UMR CNRS 5507, Place E. Bataillon, 34095 Montpellier, France Thin Solid Films 473 (2005) 49– 53
Materials Science in Semiconductor Processing 4 (2001) 611–616
摘要
The MBE growth of ZnSSe alloy thin films on ITO substrates using ZnS and Se sources was studied and various structural and opto-electronic properties of the as-grown thin films were characterised. The XRD rocking curves resulting from these films indicate that the as-grown polycrystalline ZnSSe thin films have a preferred orientation along (1 1 1) direction. The evaluated crystal sizes as deduced from the FWHM of the XRD layer peaks were found to show a strong growth temperature dependence with the optimised temperature at about 2901C. TEM measurements done on these thin films also indicate a similar growth temperature dependence. The TEM cross-sectional micrograph of the sample grown at the optimised temperature shows a well-defined columnar structure whose nucleation seems to be highly correlated with the ITO grains. UV responsivity as high as 0.01A/W and more than three orders of magnitude in rejection power for wavelengths longer than 450nm have been achieved. It was also found that the sample grown at the optimised temperature has the lowest resistivity of 4.31011Ocm, which provides a good match with that of a liquidcrystal layer. These results indicate that MBE-grown ZnSSe thin film is a promising candidate as the photoconductive material of liquid-crystal light valves for UV imaging applications
Fig. 1. (a) XRD spectrum of as-deposited ZnO film; (b) XRD spectrum of as-deposited and annealed ZnO films.
c)
Fig. 4. (a) AFM image of as-grown ZnO by reactive e-beam; (b) AFM image of the 1 h annealed ZnO at 750 8C prepared by reactive e-beam; (c) AFM image of the as-deposited ZnO by rf magnetron
实验步骤
ZnO thin films have been deposited on (100)-oriented silicon substrates by the reactive electron beam evaporation technique. The residual pressure reached in the chamber was below 1.3104 Pa, the distance between the target and the substrate was 12 cm, the substrate temperature was maintained at 100℃ and the electrons’ energy was about 5.5 keV. High-purity (99.99%) polycrystalline ZnO source has been used as an evaporation source and oxygen gas has been introduced and maintained at a pressure of 102 Pa in the evaporation chamber. Thus, the collisions of O2 molecules with both high-energy electrons and particles evaporated out from ZnO source partly ionize the O2 molecules and improve the film stoichiometry. The film growth rate, which is dependent on the substrate temperature, the oxygen pressure and the filament current of the electron beam, has ranged from 0.3 to 0.4 nm s-1. After the deposition, the films have been annealed for 1 h in air at 550 ℃ and 750℃, respectively, to investigate the effect of annealing on the electrical and optical properties