Aiying WANG
,
Kwangryeol Lee
,
Chao SUN
,
Lishi WEN
,
null
,
null
,
null
,
null
材料科学技术（英文）
During the growth of the hot filament chemical vapor deposition (HFCVD) diamond films, numerical simulations in a 2-D mathematical model were employed to investigate the influence of various deposition parameters on the gas physical parameters, including the temperature, velocity and volume density of gas. It was found that, even in the case of optimized deposition parameters, the space distributions of gas parameters were heterogeneous due primarily to the thermal blockage come from the hot filaments and cryogenic pump effect arisen from the cold reactor wall. The distribution of volume density agreed well with the thermal round-flow phenomenon, one of the key obstacles to obtaining high growth rate in HFCVD process. In virtue of isothermal boundary with high temperature or adiabatic boundary condition of reactor wall, however, the thermal round-flow was profoundly reduced and as a consequence, the uniformity of gas physical parameters was considerably improved, as identified by the experimental films growth.
关键词:
Gas physical parameters
,
physical
,
parameters
,
simulations
,
di
Hao DU
,
Jun GONG
,
Chao SUN
,
Rongfang HUANG
,
Lishi WEN
,
W.Y.Cheung
,
S.P.Wong
材料科学技术（英文）
In this work, the prerequisite and mode of electromagnetic response of Al nanofilms to electromagnetic wave field was suggested. Reflectance, transmittance in infrared region and carrier density of the films was measured. With the carrier density of the films, the dependence of their plasma frequencies on the film thickness was obtained. On the other hand, the dependence of absorptance on the frequency of electromagnetic wave field was set up by using the measured reflectance and transmittance, which provided plasma frequency---film thickness relation as well. Similarity of both plasma frequency---film thickness relations proved plasma resonance as a mode of electromagnetic response in Al nanofilms.
关键词:
Aluminum nanofilm
,
null
,
null
Aiying WANG
,
Chao SUN
,
Rongfang HUANG
,
Lishi WEN
材料科学技术（英文）
A three-dimensional model was developed to investigate the influence of various hot filaments parameters on substrate temperature fields that significantly affect the nucleation and growth of diamond films over large area by hot-filament chemical vapor deposition (HFCVD). Numerical simulated results indicated that substrate temperature varies as a function of hot filaments number, radius, temperature, emissivity, the distance between filaments, and the distance between substrate and filaments arrangement plane. When these filaments parameters were maintained at the optimal values, the homogeneous substrate temperature region of 76mm×76mm with the temperature fluctuation no more than 5% could be obtained by a 80mm×80mm hot filaments arrangement plane. Furthermore, the homogeneous region could be enlarged to 100mm×100mm under the condition of supplementary hot filaments with appropriate parameters. All of these calculations provided the basis for specially optimizing the hot filaments parameters to deposit uniform diamond film over large area by HFCVD.
关键词:
HFCVD
,
null
,
null
,
null
Wei WANG
,
Lishi WEN
材料科学技术（英文）
Fe/Ti multilayers with different modulation wavelengths (Lambda) prepared by r.f. sputtering has been investigated by using cross sectional transmission electron microscopy (XTEM). It was observed that the columnar structure, interface morphology, and metastable phase presented at the interface of the multilayer system strongly depend on the bilayer thickness (Lambda). For high period multilayers, the waviness wavelength of interfaces is about two times broader than the column diameter. For a sample with Lambda =30 nm, its column width and waviness wavelength was about 80, and 190 nm, respectively. Both of them decreased with the reduction of Lambda, so as to nearly equal values of column diameter and waviness wavelength were obtained. The Fe and Ti grains of both 30 nm and 6 nm multilayers are polycrystalline, and have a textured structure. In short bilayer thickness (Lambda =6 nm), the intermetallic compound Fe2Ti was presented at the interfaces due to solid state reaction, for Lambda =2 nm, amorphous phase Ti-rich layer was formed at the interfaces, resulting in a sharp interface multilayer structure.
关键词:
Meng CHEN
,
Xuedong BAI
,
Jun GONG
,
Chao SUN
,
Rongfang HUANG
,
Lishi WEN
材料科学技术（英文）
Indium tin oxide (ITO) films were prepared on polyester, Si and glass substrate with relatively high deposition rate of above 0.9 nm/s by DC reactive magnetron sputtering technique at the sputtering pressure of 0.06 Pa system, respectively. The dependence of resistivity on deposition parameters, such as deposition rate, target-to-substrate distance (TSD), oxygen flow rate and sputtering time (thickness), has been investigated, together with the structural and the optical properties. It was revealed that ail 110 films exhibited lattice expansion. The resistivity of ITO thin films shows significant substrate effect: much lower resistivity and broader process window have been reproducibly achieved for the deposition of ITO films onto polyester rather than those prepared on both Si and glass substrates. The films with resistivity of as low as 4.23 x 10(-4) R cm and average transmittance of similar to 78% at wavelength of 400 similar to 700 nm have been achieved for the films on polyester at room temperature.
关键词:
Xuedong BAI
,
Meng CHEN
,
Lishi WEN
,
R.F.Huang
材料科学技术（英文）
The ultrathin aluminum films with thickness in the range of 2 similar to 60 nm have been deposited by de magnetron sputtering apparatus. Reflectance and transmittance of the obtained samples were measured with a WFZ-900-D4 UV/VIS spectrophotometer. The optical constant (n, k) and permittivity (epsilon', epsilon ") were determined by applying Newton-Simpson recurrent substitution method. The results indicate that the electromagnetic constitutive characteristic of ultrathin aluminum films is a function of thickness and has obvious size effect.
关键词:
