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The properties of ZnO thin film on sapphire (0001) substrate fabricated by single source chemical vapour deposition (SSCVD) method are studied. X-ray diffraction (XRD) analysis demonstrates that the film exhibits hexagonal structures but with preferential nonpolar (100) plane orientation, which is different from the crystalline structure of substrate, and its formation mechanism is also analyzed. The film has the characteristic of p-type conductivity originating from excess of oxygen, and its p-type conductivity is comparatively stable due to its nonpolar plane orientation. A strong ultraviolet (UV) emission and a high light transmission in visible wavelength region are observed from photo-luminescence (PL) spectrum and transmittance spectra at the room temperature, and the strong ultraviolet emission originates from the recombination of free and bound excitons. Compared with the ZnO film on silicon substrates, the exciton emission peaks of the film on sapphire substrate show a slight blue shift about 50 meV, which might be related to the different crystallite sizes or surface stress of the films. 相似文献
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在Ar气气氛下对热氧化n型4H-SiC生长的SiO2薄膜进行了1100 ℃以下不同温度的退火, 采用反射式椭圆偏振光谱、红外透射光谱研究了退火温度对SiO2薄膜致密性的影响. 椭偏测试的结果表明, 600 ℃退火后样品具有最大的折射率1.47和最小的厚度84.63 nm. 红外研究的结果显示, 600 ℃退火后LO峰强度最强, 认为是对应Si-O结构单元浓度最高. Al/SiO2/SiCMOS结构SiO2的漏电特性研究表明, 600 ℃退火后的SiO2薄膜漏电流相比于其他温度退火的氧化层漏电流小了两个数量级. 在外加反向偏压5V时, 漏电流密度仅仅只有5×10-8 A/cm2.600 ℃退火能显著地改善热氧化层SiO2的致密性. 相似文献
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The stable properties of N-doped p-type ZnO thin films with preferential nonpolar (100) plane orientation relative to polar (002) plane orientation are investigated. The two kinds of oriented thin films are fabricated by the methods of post heat treatment and double sources in situ, respectively. The Hall investigations demonstrate that N-doped p-type ZnO thin films with preferential nonpolar (100) plane orientation are more stable, and the results are also proved by build-in electric field model and electronic structure calculations of the films based on the first orinciple. 相似文献
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采用高真空电子束蒸发法制作了基于4H SiC外延材料的肖特基二极管,其中欧姆接触材料为Ti/Ni,肖特基接触材料为Ni。常温下,电流-电压(I-V)测试表明Ni/4H SiC肖特基二极管具有良好的整流特性,热电子发射是其主要输运机理。对比分析不同快速退火温度下器件的I-V特性,实验结果表明875 ℃退火温度下欧姆接触特性最好,400 ℃退火温度下器件肖特基接触I-V特性最好,理想因子为1.447,肖特基势垒高度为1.029 eV。 相似文献