多孔硅薄膜对p 型单晶硅太赫兹波段透射特性的影响

利用化学腐蚀方法，在低阻值p型单晶硅片上制备了火山口形、准纳米孔柱形和多孔形三种形貌的多孔硅薄膜。以空气为参考基准，0.2～10 THz时域光谱显示，火山口形样品在0.2～6 THz的透射强度下降了约1/2，另外两种样品强度下降了约1/5。火山口形、准纳米孔柱形样品呈现低通滤波特性，多孔形样品呈现级联带通特性。准纳米孔柱形样品截止频率比火山口形样品和多孔形样品提高了3 THz左右。样品的频谱出现多处吸收峰，峰的位置与薄膜的几何结构尺寸有关。实验结果表明:多孔薄膜的形状和几何结构尺寸改变了p型单晶硅的太赫兹波段透射强度、吸收频率和截止，该材料可以成为从太赫兹波段至可见光波段的宽频段探测材料和调制材料。

Affect of porous silicon film on transmission characteristics of p-type monocrystalline silicon in terahertz band

Porous silicon thin films were prepared by chemical etching method on monocrystalline silicon surface. P-type morphology of these films exhibited three tapes: crater, quasi nano-pillar-array and porous. Terahertz time domain spectroscopy of these samples from 0.2-10 THz showed that transmitted intensity of these samples was very different. Taking air as the reference, transmission intensity of crater sample from 0.2 to 6 THz dropped by about one half and intensity of other two samples only decreased about by one fifth. For filter characteristics, samples of crater one and quasi nano-pillar-array one had low-pass characteristics and porous sample had cascade band-pass characteristic. Cut-off frequency of quasi nano-pillar-array sample improved 3 THz than others. Furthermore, there were much absorption peaks in samples and positions of these peaks had very closed relationship to the micro-surface-structures of porous silicon films. Experiments showed that, both shape and size of these films appeared to change and control transmission properties of monocrystalline silicon in terahertz such as transmitted intensity, absorption frequency and cut-off frequency. So porous silicon can be a new wide spectral detecting and modulation materials from terahertz to visible light.