以無電鍍蝕刻方式探討矽奈米線陣列合成與光學應用

Abstract

矽奈米線因其特殊性質已被發展為各式元件，其具有極大潛力並受到學術界注意。本研究利用一種無電鍍蝕刻（Electroless metal deposition，EMD）的方法，解決以固－液－氣法合成矽奈米線的諸多缺點。此方法可在常壓、大氣、水相條件下，不需外加任何形式能量，即可利用自發的電化學反應，以硝酸銀（AgNO3）與氫氟酸（HF）混合溶液在矽晶片表面成長出高密度且垂直之單晶矽奈米線。在本研究主要探討兩部分，分別為（1）以無電鍍蝕刻製備大面積且準直的矽奈米線陣列與（2）製作二氧化鈦與矽奈米線之無機-無機之異質接面型太陽能電池。 第一部分為以硝酸銀（AgNO3）與氫氟酸（HF）混合溶液，於溫度50℃環境下，可獲得大面積且準直的矽奈米線陣列，可得到單晶的矽奈米線，且與原矽基板方向一致，其奈米線長度與蝕刻時間呈線性之趨勢，且在蝕刻時間為45分鐘時可得到最佳的抗反射特性（3.07%在可見光範圍內）及準直的奈米線陣列。第二部分為矽奈米線陣列表面濺鍍二氧化鈦薄膜形成p-n接面，其晶體結構為銳鈦礦與金紅石礦兩種結構混合。在本研究中，使用二氧化鈦與矽奈米線製作形成無機-無機之異質接面型是少見的太陽能電池。就目前結果得知，使用矽奈米線陣列當基板比使用晶圓來的優異，其Voc為0.139V，Jsc為94.81 mA/cm2，FF為21.3%及效率為2.81×10-3%。

Recent years have seen increased attention given to silicon nanowires (SiNWs), owing to their unusual quantum-confinement effects for developing various applied device, such as optoelectronics, biosensor, and other devices. Therefore, the aims of this study are divided into two sections, (1) a simple and convenient approach to generate SiNWs of single-crystalline, well-aligned, and large area has been directly synthesized on p-type (100) silicon wafer via an electroless metal deposition (EMD) method and (2)a n-type TiO2 thin films were deposited sputtering on the p-SiNW arrays by RF magnetron sputter to form a inorganic-inorganic heterojunctions solar cell . Large-area ordered single crystal SiNW arrays on p-type (100) silicon wafer without the use of a template were prepared in a silver nitrate and hydrofluoric acid (HF/AgNO3) solution at 50oC. The result showed that highly dominant peak at 69° is belong to (004) silicon plane which can be explained equally by preferential etching along [100] directions. The linear relationship of SiNW arrays could be adjusted by controlling the etching time. Besides, the result showed that SiNWs gave the best anti-reflective properties (3.07% in the broad visible band) and well-aligned properties with 45 minutes. A n-TiO2/p-SiNW heterojunction has been fabricated by RF magnetron sputter. The crystal structure of TiO2 layer reveal its anatase and rutile both structured hybrid. A n-type TiO2 thin films were deposited sputtering on the p-SiNW arrays having hydrophilicity features.. In this study, a rare inorganic-inorganic heterojunction solar cells using titanium dioxide and silicon nanowires was fabricated. The present results indicated that the power conversion efficiency (PCE) of n- TiO2/p-SiNWs better than n- TiO2/p-Si inorganic-inorganic heterojunction solar cells. The inorganic-inorganic heterojunction solar cells used itanium dioxide and silicon nanowires , in which the Voc is of 0.139V, Jsc is of 94.81 mA/cm2 and, the FF is of 21.3% and efficiency is of 2.81 × 10-3%.