【摘要】 采用水热腐蚀技术在单晶硅衬底上制备出一种新的硅微米 /纳米结构复合体系——硅纳米孔柱阵列 (Si -NPA) ,并对其表面形貌、结构及光学特性进行研究 .Si NPA的结构复合性体现为在微米和纳米两个尺度上形成了三个分明的结构层次 ,即微米尺度的硅柱阵列结构、硅柱上的纳米多孔结构以及组成孔壁的硅纳米晶粒 .积分光反射谱和荧光光谱测试表明 ,Si -NPA具有良好的光吸收和光致发光特性 .依据Si -NPA积分反射谱的实验数据 ,采用Kramers Kronig变换关系计算得到了Si- NPA的复折射率和复介电函数、吸收系数等光学常数 ,并由此讨论了Si- NPA相对于单晶硅的光学特性发生显著变化的原因 .最后 ,通过分析Si- NPA的光吸收系数与入射光子能量之间的关系 ,揭示出Si- NPA具有直接带隙半导体的电子结构特征 ,而且理论计算得到的Si- NPA的带隙能与其光致发光谱的峰位能很好符合 .更多还原

【Abstract】 A novel silicon-based micron/nanometer structural composite system, silicon nanoporous pillar array(Si-NPA), was prepared on the substrate of single-crystal silicon (sc-Si) wafers by a hydrothermal etching method; and the studies on its morphological structural and optical properties were carried out. Structural experiments disclose that Si-NPA could be well described by triple hierarchical structures: the array composed of micron-sized silicon pillars, the nanopores densely distributing on each pillar, and the silicon nanocrystallites constructing the walls of nanopores. Optical measurements prove that Si-NPA has good performances on light absorption and photoluminescence(PL). Based on the experimental data of the integral reflectance spectrum, the structural and optical parameters such as complex refractive index, complex dielectric constant and absorption coefficient of Si-NPA are calculated by adopting Kramers-Kronig transformation; based on which, the origin of the notable difference between the optical properties of Si-NPA and sc-Si is discussed. Through analyzing the function relation between the absorption coefficient of Si-NPA and the photon energy of incident light, the characteristic of the electronic structure of Si-NPA is proved to be that of a direct-band-gap semiconductor, and the calculated bandgaps agree well with the PL peak energies given by experiments.更多还原