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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,0.2~10THz时域光谱显示,火山口形样品在0.2~6THz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。
Porous silicon films with three morphologies of volcanic shape, quasi-nanopore cylindrical shape and porous shape were prepared on low resistance p-type monocrystalline silicon wafers by chemical etching. Taking the air as the reference, the time-domain spectra of 0.2 ~ 10THz showed that the transmission intensity of volcanic shaped samples decreased by about 1/2 at 0.2 ~ 6THz, and the other two samples decreased by about 1/5. The crater-like and quasi-nanopore cylindrical samples show low-pass filter characteristics, and the porous samples show cascade band-pass characteristics. The cutoff frequency of quasi-nanopore cylindrical samples is about 3 THz higher than that of crater-shaped and porous samples. The spectrum of the sample appears multiple absorption peaks, the location of the peak and the film geometry size. The experimental results show that the shape and geometry of the porous film change the terahertz band transmission intensity, absorption frequency and cut-off of p-type single crystal silicon. The material can be a wide band detection material and a modulation material from the terahertz band to the visible band .