【作者】 张常军；

【导师】 陈治明； 卢刚；

【作者基本信息】 西安理工大学 ， 材料物理与化学， 2004， 硕士

【摘要】 多孔半导体材料在最近几年引起了人们的广泛研究，其原因是由于它具有比原始材料更短的光致发光波长和更高的发光效率。其中多孔碳化硅就比晶体SiC有更高的发光效率。本文分别以微米和纳米碳化硅粉末为原料，采用粉末冶金的烧结工艺，成功的制备了纳米多孔碳化硅，并分析了多孔碳化硅的结构，同时测试了其光致发光谱。 多孔碳化硅的制备过程包括原始粉末的净化、压坯的压制、烧结过程和烧结样品的后续处理。对于微米粉末，压坯在750MPa压力下压制成型，烧结温度为1600～1800℃，烧结时间为4～7h；而对于纳米碳化硅粉末，压坯在1000MPa压力下压制成型，烧结温度为1600℃，烧结时间为4～5h，所有压坯都在1.0 atm的Ar．气保护下进行烧结，烧结完成后，用干氧法在氧化炉中氧化并研磨或直接研磨的方法去除样品表面过量的碳。 使用SEM和XRD对样品的结构和组成进行了分析。结果显示对纳米碳化硅粉末在1600℃，4h30min-4h50min条件下烧结制备的样品具有大量的微孔，平均孔径尺寸达到纳米数量级，约为80-90nm。样品的晶型也发生了转变，1600℃，4h30min以上时间烧结时，4H-SiC晶型信号很弱，基本消失。 用He-Cd激光器(325 nm，10mW)对样品的光致发光进行了测试。对于纳米多孔碳化硅，所有样品的发光主峰都位于2.69eV附近，在3.0eV附近处有一肩峰。发光峰的强度随着烧结时间的增加略有下降，多孔碳化硅的发光来自于缺陷态。更多还原

【Abstract】 Porous semiconductor materials have been widely researched in recent years ,the reason is that they have shorter photoluminescence wave length and higher emission efficiency than the origin materials, porous SiC is one of them which has much higher photoluminescence (PL) emission efficiency than bulk SiC. In this paper, micrometer and nanometer SiC powder were respectively sintered as employed in powder metallurgy ,nanometer porous SiC was successfully prepared with its microstructure analyzed and its photoluminescence tested.The preparation process of sintered PSC involved powder purifying, pressed powder compact preparation, sintering process and final treatment. To micrometer SiC powder, Pressed compacts were made under 750 Mpa pressure with sintering time ranging from 4 to 7h and sintering temperature ranging from 1600 to 1800@,but to nanometer SiC powder, Pressed compacts are made under1000 Mpa pressure with sintering temperature being 1600 癈 and sintering time ranging from 4 to 5h.Howerver ,all compacts were sintered under an Ar protection of 1.0 atm pressure. After sintering, the samples are dry-oxidized in an oxidization furnace and then have their excessive carbon removed by diamond-cream grinding or direct grinding.The preparation process of sintered PSC involves powder purifying, pressed powder compact preparation, sintering process and final treatment, various s ranging from 500 to lOOOMPa. Sintering time ranges from 3 to 10 hours, and sintering ranges from 1600@ to 1900@, After sintering, the samples are dry-oxidized in an oxidization furnace and then have their excessive carbon removed by diamond-cream grinding or direct grinding.Its structure and composition were analyzed by SEM and XRD. The results show thatsamples sintered under the condition of 1600@ and 4h30min-4h50min using nanometer SiC powder had plenty of micro cavities, whose sizes were in nanometer order and were about 80~90nm,and at the same time the microstructure of the samples were changed ,if sintering time was over 4h30min, the signal of 4H-SiC was very weak and even disappeared.Its PL spectrum is measured under the excitation of an ultraviolet (UV) light beam from a He-Cd laser (325 nm, lOmW). All nanometer porous samples have a major peak at 2.69eV and a minor one at 3.0eV at room temperature, the intensity of luminescence peak declined as the sintering time prolonged. A defect model is suggested to account for the PL of sintered PSC.更多还原