多孔矽材料因其具有低熱傳導係數特性，利用奈米結構的尺寸效應能使有效熱傳導係數大幅下降，隨著微奈米技術的發展成熟，相繼有許多多孔矽材料的新興應用，其中近年來非均質多孔矽受到關注，非均質多孔矽其結構上在不同位置有著相異的孔隙率，因其結構特性發現具有疏密變化的非均質多孔矽結構有熱整流現象，使熱傳率在正向與反向有所不同。多孔矽之製備包括乾蝕刻、電化學蝕刻、金屬輔助化學蝕刻等。本研究利用兩歩式金屬輔助化學蝕刻法具有製程相對簡單、製備成本低之優點，研究探討不同沉積與蝕刻參數對多孔矽結構影響，最後製備非均質多孔矽結構，並利用雷射閃光法量測其熱擴散係數。 接著探討非均質多孔矽之熱傳性質，利用熱傳數學模型分析在孔隙率影響下對熱傳導係數影響，研究結果顯示在低孔隙率下，均質多孔矽結構與非均質多孔矽結構之熱傳導係數差異不大。最後藉由非均質多孔矽結構之孔隙率的變化，再透過熱傳導係數對溫度的相依，使多孔矽結構因孔隙率及溫度的不同改變其熱傳導係數，預測其熱整流效率。 ;As porous silicon materials exhibit low thermal conductivity technology characteristics, using the size effect of nanostructures can significantly lower the effective thermal conductivity coefficient. Owing to the mature development of micro-nano technology, various emerging applications of porous silicon materials have been proposed successively. Recently, applications of inhomogeneous porous silicon materials have attracted great attention. Inhomogeneous porous silicon characterized by diversified porosity at various places in its structure. The inhomogeneous porous silicon system with porosity differences has been found to exhibit thermal rectification phenomenon, leading to the rate of heat transfer vary in both forward and backward direction owing to its structural characteristics. Common processes for the synthesis of porous silicon materials include dry etching, electrochemical etching and metal-assisted chemical etching. In this study, metal-assisted chemical etching was employed due to its advantage of relatively facile process and low cost. This study explores the etching parameters and their impact on the porous structure of silicone and consolidates the effects of these parameters to synthesize an inhomogeneous porous silicon structure and the coefficient of thermal diffusion is measured by the laser flash method. The thermal conductivity properties of inhomogeneous porous silicon materials were discussed. Using the mathematical model of heat transfer to analyze the influence of the porosity on the thermal conductivity coefficient. The research results show that at low porosity, the thermal conductivity coefficients of the homogeneous porous silicon structure and the inhomogeneous porous silicon structure are similar different. Eventually, the porosity of the inhomogeneous porous silicon structure and the thermal conductivity reliance on temperature are used to adjust the porous silicon structure owing to the varying porosity and temperature thermal conductivity coefficient, and predict its efficiency of thermal rectification efficiency.
