Diamond like carbon films were synthesized by the pulsed laser deposition method under a magnetic filed. The magnetic field was used to enhance the hardness of the films. Analysis with transmission electron microscop...Diamond like carbon films were synthesized by the pulsed laser deposition method under a magnetic filed. The magnetic field was used to enhance the hardness of the films. Analysis with transmission electron microscopy and atomic force microscopy were carried out to characterize the films. As a protective coating, the film was deposited on porous silicon. The influence of the coating on the photoluminescence properties of porous silicon was studied.展开更多
Vertical gradient freezing (VGF) growth of Hg1-xCdxTe (x=0.19) was studied. Porosity can be eliminated by adjusting temperature program of growth. As expected, subgrain boundaries and etch pit densities can be reduced...Vertical gradient freezing (VGF) growth of Hg1-xCdxTe (x=0.19) was studied. Porosity can be eliminated by adjusting temperature program of growth. As expected, subgrain boundaries and etch pit densities can be reduced considerably if low temperature gradient is used.展开更多
oron carbon nitride coatings were synthesized using the pulsed laser deposition method. The hardness of the coatings was measured by a Vickers microhardness tester. It was found that the hardness of the coatings was b...oron carbon nitride coatings were synthesized using the pulsed laser deposition method. The hardness of the coatings was measured by a Vickers microhardness tester. It was found that the hardness of the coatings was between 15.45 and 34.05 GPa under a load of 0.5 N. The surface morphology was studied by optical microscopy and atomic force microscopy. There were spherical and irregular shaped particulates in the coatings. The density of the spherical particles was found being increased at high deposition temperatures. The rootmeansquared surface roughness of the coatings was about 4 nm.展开更多
ased on Marvin L. Cohen′s empirical approach, a simple model of calculation of bulk moduli of carbon nitride/metal nitride composites is shown. The calculated bulk modulus of the crystalline carbon nitride/TiN compos...ased on Marvin L. Cohen′s empirical approach, a simple model of calculation of bulk moduli of carbon nitride/metal nitride composites is shown. The calculated bulk modulus of the crystalline carbon nitride/TiN composite coating is comparable with that of cBN and diamond. This model predicts that the modulus of the composite is between the moduli of the two components.展开更多
In CdZnTe crystal growth by vertical gradient freezing (VGF) method the porosity control, preventing the inner-wall carbon coating from breakdown and preventing backdiffusion from the melt were studied. The porosity c...In CdZnTe crystal growth by vertical gradient freezing (VGF) method the porosity control, preventing the inner-wall carbon coating from breakdown and preventing backdiffusion from the melt were studied. The porosity can be eliminated by maintaining a proper temperature gradient at the solid/liquid interface during growth. High vapor pressure in the growth chamber sometimes causes expansion of the quartz ampoule and thus breakdown of the inner-wall carbon coating. Backdiffusion can be controlled by reducing the opening size of the reservoir and the volume of the ampoule's free space.展开更多
Two methods used to grow adherent coatings, roughening of the surface for mechanical interlocking and the use of chemically compatible interlayers having intermediate thermal expansion coefficients are analyzed numeri...Two methods used to grow adherent coatings, roughening of the surface for mechanical interlocking and the use of chemically compatible interlayers having intermediate thermal expansion coefficients are analyzed numerically with the aid of phase diagram. Calculations indicate that more roughness and smaller periodicity of the substrate surface will increase the interfacial area and thus enhance the adherence strength of the coating. The phase diagram shows that an intermediate layer with a proper composition gradient from the substrate to the film will relax the thermal stress at the interface effectively.展开更多
Adhesion of carbon films on quartz is a critical issue in CdZnTe crystal growth. The carbon films do not stick well to quartz with a smooth surface. Strong adhesion is obtained when the quartz is abraded by abrasive p...Adhesion of carbon films on quartz is a critical issue in CdZnTe crystal growth. The carbon films do not stick well to quartz with a smooth surface. Strong adhesion is obtained when the quartz is abraded by abrasive paper (made of SiC).展开更多
A simple method of carbon film coating used in CdZnTe crystal growth was developed. The optimum parameters were selected. Breakdown of carbon film was commonly seen if Cd reservoir was not used in the crystal growth. ...A simple method of carbon film coating used in CdZnTe crystal growth was developed. The optimum parameters were selected. Breakdown of carbon film was commonly seen if Cd reservoir was not used in the crystal growth. The carbon film was in good condition when the vapor pressure of Cd was kept around 0.1 MPa during crystal growth.展开更多
The method of vertical Bridgman seeded growth of Cdi.Zn.Te crystals was studied. This method ispromising in obtaining large size single crystals and improving the crystal structure. However, some prob-lems such as see...The method of vertical Bridgman seeded growth of Cdi.Zn.Te crystals was studied. This method ispromising in obtaining large size single crystals and improving the crystal structure. However, some prob-lems such as seeded growth failurc exist at present.(111)-oriented Cd_(0.96)Zn_(0.04)Te single crystal substrateswith size greater than 15×15 mm￣2 arc obtained. The FWHM ranges from 18 to 66 arc.sec and theresistivity is greater than 10￣6 obmem.展开更多
文摘Diamond like carbon films were synthesized by the pulsed laser deposition method under a magnetic filed. The magnetic field was used to enhance the hardness of the films. Analysis with transmission electron microscopy and atomic force microscopy were carried out to characterize the films. As a protective coating, the film was deposited on porous silicon. The influence of the coating on the photoluminescence properties of porous silicon was studied.
文摘Vertical gradient freezing (VGF) growth of Hg1-xCdxTe (x=0.19) was studied. Porosity can be eliminated by adjusting temperature program of growth. As expected, subgrain boundaries and etch pit densities can be reduced considerably if low temperature gradient is used.
文摘oron carbon nitride coatings were synthesized using the pulsed laser deposition method. The hardness of the coatings was measured by a Vickers microhardness tester. It was found that the hardness of the coatings was between 15.45 and 34.05 GPa under a load of 0.5 N. The surface morphology was studied by optical microscopy and atomic force microscopy. There were spherical and irregular shaped particulates in the coatings. The density of the spherical particles was found being increased at high deposition temperatures. The rootmeansquared surface roughness of the coatings was about 4 nm.
文摘ased on Marvin L. Cohen′s empirical approach, a simple model of calculation of bulk moduli of carbon nitride/metal nitride composites is shown. The calculated bulk modulus of the crystalline carbon nitride/TiN composite coating is comparable with that of cBN and diamond. This model predicts that the modulus of the composite is between the moduli of the two components.
文摘In CdZnTe crystal growth by vertical gradient freezing (VGF) method the porosity control, preventing the inner-wall carbon coating from breakdown and preventing backdiffusion from the melt were studied. The porosity can be eliminated by maintaining a proper temperature gradient at the solid/liquid interface during growth. High vapor pressure in the growth chamber sometimes causes expansion of the quartz ampoule and thus breakdown of the inner-wall carbon coating. Backdiffusion can be controlled by reducing the opening size of the reservoir and the volume of the ampoule's free space.
文摘Two methods used to grow adherent coatings, roughening of the surface for mechanical interlocking and the use of chemically compatible interlayers having intermediate thermal expansion coefficients are analyzed numerically with the aid of phase diagram. Calculations indicate that more roughness and smaller periodicity of the substrate surface will increase the interfacial area and thus enhance the adherence strength of the coating. The phase diagram shows that an intermediate layer with a proper composition gradient from the substrate to the film will relax the thermal stress at the interface effectively.
文摘Adhesion of carbon films on quartz is a critical issue in CdZnTe crystal growth. The carbon films do not stick well to quartz with a smooth surface. Strong adhesion is obtained when the quartz is abraded by abrasive paper (made of SiC).
文摘A simple method of carbon film coating used in CdZnTe crystal growth was developed. The optimum parameters were selected. Breakdown of carbon film was commonly seen if Cd reservoir was not used in the crystal growth. The carbon film was in good condition when the vapor pressure of Cd was kept around 0.1 MPa during crystal growth.
文摘The method of vertical Bridgman seeded growth of Cdi.Zn.Te crystals was studied. This method ispromising in obtaining large size single crystals and improving the crystal structure. However, some prob-lems such as seeded growth failurc exist at present.(111)-oriented Cd_(0.96)Zn_(0.04)Te single crystal substrateswith size greater than 15×15 mm￣2 arc obtained. The FWHM ranges from 18 to 66 arc.sec and theresistivity is greater than 10￣6 obmem.
