此計畫將以本實驗室所研發的旋轉塗佈摻雜源(spin-on dopant, SOD)技術為基礎來開發結合SOD之局部雷射摻雜(laser doping)擴散製程。此製程技術將用來製作選擇性射極(selective emitter, SE)結構於雙面N型PERT(鈍化射極及背面全擴散)太陽能電池。相較於傳統的氣體摻雜源(BBr3)，SOD製程技術具有成本低、安全性高等優點；另一方面相較於離子佈植與短波長雷射系統，我們將開發以二氧化碳(CO2)雷射進行局部高摻雜SE結構製作，將能有效地降低設備成本並預期可降低製程中表面缺陷的產生。 本計畫的技術特點是以硼SOD形成之borosilicate glass (BSG)直接吸收CO2雷射能量，進而在矽晶片表面形成局部高摻雜濃度區域。首先將調控SOD與CO2雷射擴散製程參數以有效控制摻雜濃度與縱深分布，此部分將輔以模擬計算CO2雷射對BSG-coated矽晶片加熱時之溫度分布情形，以減少調整製程參數時間並可針對電池所需之摻雜濃度與分布進行製程參數最佳化。此外，我們也將優化CO2雷射擴散摻雜製程條件來減少表面缺陷並降低表面少數載子複合速率，目標將製作出具低片電阻及高載子生命週期之SE結構。在應用於製作雙面SE N-PERT電池方面，將由本實驗室於學校先進行小面積電池製作驗證其可行性後，再將此製程技術移植至合作公司廠內進行大面積電池之試作。最終希冀能協助合作廠商建立一先進的SE製作技術，並做為下一代N-PERT電池的標準製程。 ;In this project, a local laser-doping technique based on a spin-on-dopant source and carbon dioxide (CO2) laser will be developed with the purpose of implementing selective emitter (SE) structures in bifacial n-type PERT (passivated emitter rear totally diffused) silicon solar cells. At the first stage of this project, the SOD and laser-doping process parameters will be optimized in order to obtain the optimized dopant concentration and depth profile. The main laser parameters studied will be the average power output and the pulse repetition frequency. In addition, the simulation of optical coupling of laser sources will be carried out, and characteristic behavior of temperature profiles during laser-doping will be illustrated. We will also investigate the formation of defects during laser processing and try to minimize the defects and surface recombination velocity by adjusting the process parameters. Based on the experimental results, the optimized process steps will be suggested for fabrication of bifacial SE N-PERT solar cells. The ultimate goal of this project is to assist our collaborator (Taiwan Solar Energy technology Co., Ltd.) to integrate this process technology into the production line of the conventional cell process, and increase the cell efficiency by 0.3 abs% compared to conventional N-PERT cells.
