應用能帶圖輔助解析n型矽之光電化學蝕刻機制; Energy band diagram for the photo-electrochemical etching reaction of n-type (100) silicon

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Title:	應用能帶圖輔助解析n型矽之光電化學蝕刻機制;Energy band diagram for the photo-electrochemical etching reaction of n-type (100) silicon
Authors:	鄭文達;Wern-Dare Jheng
Contributors:	機械工程研究所
Keywords:	光電化學蝕刻;能帶圖;矽蝕刻;photo-electrochemical etching;energy band diagr
Date:	2005-05-03
Issue Date:	2009-09-21 11:44:25 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究之目的在於建立n-型矽(100)於不同實驗條件下光電化學蝕刻之熱力學能帶圖。藉由能帶圖求得反應活化能，並配合動力學量測所得電流-電壓(i-V)數據與SEM蝕孔形貌觀察，推測n-型矽(100)在(1)不同照光強度下(2)不同濃度氫氟酸溶液中(3)不同濃度酒精添加下之蝕刻反應機制。 n型矽/氫氟酸界面間能帶圖之繪製，首先在HF蝕刻液中藉由量測n-Si 的開路電位(Open circuit potential, OCP)與平坦電位(Flatband voltage; Vfb)，配合半導體能帶結構中費米能階（Fermi energy ; EF) 、導帶（Conduction band energy ; Ec)及價帶（Valence band energy ;Ev)的關係式，而建立出定量能帶圖。研究結果顯示：(1)n型矽的光電化學蝕刻反應，隨著照光強度從15W增加至45W，其蝕刻速率呈線性增大(2)氫氟酸濃度在0~2M時以2M蝕刻速率最快，一旦濃度超過2M，蝕刻速率反而下降(3)當添加酒精至氫氟酸中時，蝕刻速率會隨酒精濃度增加(0M~10M)而提升並促進蝕孔表面平滑，但添加過量時(15M)則會造成孔洞側蝕的現象。依據本論文所建立的能帶圖，可以對此n型矽/氫氟酸系統的光電化學蝕刻反應之行為及機制做出合理解釋。 The aim of this work was to build a thermodynamic energy band diagram for the system of n-type Si (100)/HF that is in dynamic equilibrium at the interface. The concept of the diagram was based on the shift of energy levels such as Fermi energy (EF), conduction band energy (Ec), and valence band energy (Ev) before and after the contact of silicon with HF solutions. Through measurements of the open circuit potential (OCP) and flatband voltage (Vfb), the energy band diagram for the Si/HF system was established. This diagram was useful in estimation of the activation energy for the photo-electrochemical etching system. The kinetic study demonstrated that the etching rate of the silicon (1) increases with an increase of illumination power; (2) increases to a maximum with HF from 0.5 to 2.0 M then decreases with further increase of the HF concentration; (3) accelerates in the presence of 5-10 M EtOH to form smooth macropores but decelerates and caues severe side-etching on the pore walls with the concentration of EtOH reaching 15 M. Based on the energy band diagram established and the electrochemical kinetic data measured, the author was in an attempt to make clear the mechanism for the photo-electrochemical reaction of the n-Si/HF system.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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