硼摻雜效應於超高密度矽量子點薄膜之研究

Abstract

為了縮短矽量子點間距以提升載子穿隧機率，我們之前已提出並成功開發以漸變矽過多氧化矽多層膜(Gradient Si-rich oxide multilayer, GSRO-ML)結構製作出超高密度矽量子點薄膜。在此篇論文中，我們則針對硼摻雜效應與量子點尺寸效應對於此超高密度矽量子點薄膜特性之影響做更進一步探討與研究。在硼摻雜效應下，隨著硼濺鍍功率增加，我們觀察到高結晶率矽量子點保持與些微縮小的能隙變化，而在硼濺鍍功率從0增加至25W時，由於有效活化硼摻雜原子增加，可使薄膜電性與元件光伏特性皆有明顯提升，但當硼濺鍍功率高於30W時，則會受限於非有效活化硼摻雜原子增加與硼原子於界面過度擴散導致薄膜與元件的整體效益皆明顯下降。然而，我們也驗證藉由插入一低硼摻雜濃度的GSRO-ML可大幅改善此界面過度擴散的問題並有效提升元件效益。在量子點尺寸效應下，藉由增加GSRO-ML的成核層厚度，從薄膜的光學吸收與元件的量子效率響應譜圖皆清楚觀察到紅移現象，證實了矽量子點尺寸效應的貢獻。因此，在此篇論文中，我們驗證了硼摻雜與量子點尺寸效應對矽量子點薄膜特性的顯著影響，未來將針對薄膜厚度和硼摻雜濃度與分佈等關鍵因素做更進一步的優化，以更提升元件工作效益。

In order to further reduce quantum dot (QD) separation, we had proposed and successfully developed the gradient Si-rich oxide multilayer (GSRO-ML) structure for the super-high density Si QD thin films with larger carrier tunneling probability. In this study, we investigate the B-doping and QD size effects on the super-high density Si QD thin films by using a GSRO-ML structure. Under B-doping effect, the preserved high crystallinity of Si QDs and the slightly reduced Eg with increasing PB are observed, besides, the electrical and PV properties are enhanced with increasing PB from 0 to 25W due to the increased active B-doped atoms but degraded at the higher PB than 30 W due to the increased inactive B-doped atoms and the interfacial over-diffusion of B-doped atoms. The decreased VOC with increasing PB due to the interfacial over-diffusion is efficiently improved by inserting the lowly B-doped GSRO thin films as buffer layers. Under QD size effect, the red-shift effect is clearly confirmed in the absorption band edge and quantum efficiency response with increasing NL thickness. Therefore, our results had demonstrated the feasibility and great potential for the higher efficiency Si-based solar cells integrating Si QDs by using a GSRO-ML structure.