物理科学与技术学院知识库

SiC 材料是第三代半导体核心材料之一，具有优异的物理化学特性，如高击穿场强、高熔点、饱和电子漂移速度大等，在高温、高频、大功率和抗辐射器件方面具有极其重要的应用价值，具有巨大的发展潜力和应用前景。但是由于 SiC是一种间接带隙半导体材料，其在光学方面上的应用受到了很大限制。对于提高间接带隙半导体材料的发光效率，一般有以下两个途径。其一，降低材料的维数， 这将使材料的发光效率得到显著提高。 其二， 就是引入发光中心，以提高其发光效率。
本论文针对上述问题，制备了两种模板物质（多孔硅（PS）和阳极氧化铝模板（AAO）），研究了它们的基本性质，并利用这两种模板制备了低维的 SiC 纳米材料， 同时利用共溅射方法引入了稀土元素作为发光中心。主要开展了以下工作：
（Ⅰ）利用阳极电化学腐蚀法在 p,n 型 Si 片上制备了多孔硅（PS），对制备及后处理条件进行了研究，用以提高 PS 的稳定性。
利用 PS 作为衬底，用射频溅射法沉积了 SiC 材料，通过对衬底温度，溅射气压，溅射功率等制备条件的控制，合成低维 SiC 材料。通过对后处理条件的改变，来提高材料的性质。在 PS 衬底上利用共掺杂的方法制备低维的 SiC：Tb 材料，研究 Tb 对 SiC发光的影响。利用 SEM，AFM，XRD，FTIR 表征了材料的形貌，成键等结构信息，同时对材料的结构和 PL 性质等性质进行了测试。
（Ⅱ）利用阳极电化学法在常温和低温下制备出了孔洞有序的通孔和非通孔的多孔氧化铝模板。详细研究了制备条件对模板有序性的影响。系统地研究了 AAO 模板的发光机理。用 Ar 离子对 AAO 模板进行了处理，首次发现了表面效应对 AAO 发光的影响， 澄清了表面和内部对 AAO 发光上的不同作用，首次提出了一种改进的模型来解释 AAO 模板的发光机理。
以通孔和非通孔的 AAO 作为模板，用射频溅射法制备了低维 SiC 纳米材料，系统地研究了制备条件对材料形成的影响，以及其形成机理。研究了制备条件对PL 的影响。

Silicon carbide (SiC) with remarkable chemical, thermal and mechanical stability is one of the primary materials of the third era semiconductor. It is a promising candidate for a broad variety of applications such as high-power, high-speed, and high-frequency devices which can be operated under extreme environmental conditions, but as we know, the silicon carbide is an indirect band gap material, which limits the applications on optic aspects.
There are two ways to improve the luminescence efficiency of indirect band gap semiconductor, one is lowering the dimension of materials, the other is introducing luminescent centers into the materials, and these two ways can remarkably improve the luminescence efficiency and intensity.
our work is to solve these above problems, we prepared two kinds of templates which are porous silicon (PS) and anodic alumina oxide (AAO), we have studied the basic properties such as structure, photoluminescence etc, of them, and used them to fabricate low dimensional silicon carbide nanomaterials, we used the sputtering methods to introduce rare earth into silicon carbide as the photoluminescent center. The main works we have done are as below:
(Ⅰ) the porous silicon were prepared on p and n type silicon wafer using electrochemical anodic oxidation etching method. We have studied the effects of preparing conditions and post-treatment on the properties of porous silicon.
The silicon carbide was deposited on porous silicon substrates by radio frequency sputtering, through controlling the preparing conditions such as the temperature of substrates, the pressure of sputtering gas, the power of sputtering to fabricate low dimensional silicon carbide nanomaterial.
We used co-sputtering methods to fabricate low dimensional SiC:Tb materials on porous silicon and studied the effects of Tb on the PL properties of silicon carbide that we have prepared.
We used SEM, AFM, XRD, FTIR to character the properties such as bonds,morphology, and the PL properties was studied either.
(Ⅱ) ordered porous anodic alumina oxide were prepared by second anodic oxidation at low temperature and room temperature, and their properties connected with prepared conditions were carefully studied.The PL mechanisms have been detailed investigated. We have clearly distinguished the roles of surface and interior factors on the PL properties and firstly bring forward a model to explain the PL mechanisms about the AAO templates.We have used through-pore and non-through-pore AAO templates as substrates to
fabricate low dimensional silicon carbide nanomaterials. The effects of preparing conditions on the characters of low dimensional silicon carbide were carefully studied,and the PL properties were studied either.