電化學放電加工應用於單晶矽表面粗糙化之研究;Study on texturing of mono-silicon by using Electrochemical Discharge Machining

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題名:	電化學放電加工應用於單晶矽表面粗糙化之研究;Study on texturing of mono-silicon by using Electrochemical Discharge Machining
作者:	張光華;Chang,Kuang-hua
貢獻者:	機械工程學系在職專班
關鍵詞:	電化學放電加工;表面粗糙化;單晶矽;Electrochemical discharge machining;texture;p-type silicon
日期:	2014-07-11
上傳時間:	2014-10-15 17:17:45 (UTC+8)
出版者:	國立中央大學
摘要:	為了提高太陽能電池光轉化效率，現今加工法大多使用高強酸鹼在矽晶片表面進行化學蝕刻，使其表面粗糙化藉以增加光反射次數，但是化學蝕刻法不僅加工時間長且對環境危害較大。相較於傳統太陽能表面粗糙化，本研究提出以電化學放電對於P型單晶矽進行表面粗糙化加工，加工時間短且相較於傳統化學蝕刻出的金字塔結構或是火山坑結構，電化學放電加工法可加工出較高表面粗糙度且多孔狀結構。本研究使用不鏽鋼電極為負極，正極以石墨作為輔助電極，電解液為氫氧化鉀，加工參數為加工電壓、加工時間、加工間隙、電解液濃度、添加液濃度、脈衝頻率與衝擊係數等，以電化學放電加工粗糙化後進行表面粗糙度量測，並利用三維雷射掃描式顯微鏡及掃描式電子顯微鏡觀察表面形貌。實驗過程中發現，添加適當濃度的乙醇可以幫助孔洞擴大並且提高表面粗糙化結果。在適當的加工參數加工間隙為200μm、電壓為48V、氫氧化鉀濃度為3M、乙醇濃度為4wt%、電化學放電加工1分鐘後其表面粗糙度可由0.417μm升至0.915 μm。利用積分式粗糙面反射率量測儀檢測，測量結果顯示加工前平均反射率為29.6%，經表面粗糙化後降低至12.7%。;In order to improve the light conversion efficiency of solar cells, recently processing method use the strong chemical substances to etch silicon surface. Although acid or alkaline texturing can increase the frequency of the light reflecting, this kind of texturing process not only has long processing time but also is harmful to the environment. Compared with the conventional surface texturing process which generates chemical etched pyramid structure or crater structure , this study proposes texturing P type mono-crystalline silicon by electrochemical discharge machining (ECDM). ECDM method has the advantage of short processing time and can generate a higher surface roughness and the porous structure. In this study, stainless steel was used as negative electrode. The graphite was used as the positive electrode acting as the auxiliary electrode. The potassium hydroxide was used as the electrolyte. The processing parameters include the machining voltage, the processing time, the machining gap, the electrolyte concentration, the additive agent concentration, pulse frequency and duty factor, etc. The surface roughness was measured using surface roughness tester. The surface morphology was observed using SEM and three-dimensional laser scanning microscope. The result of experiments reveals that appropriate concentrations of ethanol can expand the size of the pores and enhance surface roughening effect. The appropriate processing parameters are a machining gap of 200μm, voltage of 48V, concentration of potassium hydroxide of 3M, concentration of ethanol of 4%. The electrochemical discharge machined surface roughness was increased from 0.417μm to 0.915μm using one minute processing time. The average reflectance rate of the textured surface was decreased from 29.6% to 12.7% measuring by using integration spectroscopic reflectometer.
顯示於類別:	[機械工程學系碩士在職專班 ] 博碩士論文

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