矽基板上金催化砷化鎵奈米線太陽能電池之成長與製作

Growth and fabrication of Au-catalyzed GaAs nanowire solar cells on Si substrates

簡克任(Ke-Ren Jian)

指導教授 ： 黃金花

國立清華大學/工學院/材料科學工程學系/碩士(2012年)

摘要

相較於矽太陽能電池，砷化鎵太陽能電池具高光吸收率、直接能隙等優點，以徑向p-n奈米線結構呈現之砷化鎵太陽能電池，更具有增加載子收集能力及光吸收之優勢，對高效率太陽能電池具有極大的開發潛力。
很多研究已成功在砷化鎵基板上成長砷化鎵奈米線並組裝成太陽能電池，但鮮少於矽基板上成長奈米線並應用於太陽能電池之報導。本研究利用分子束磊晶技術，以金作為催化劑，矽與鈹作為n-type與p-type摻雜，成功地在矽基板上利用VLS機制成長具核殼結構的砷化鎵徑向p-n接面奈米線。元件製作首先將光阻旋塗在奈米線試片上作為阻擋層，接著用氧電漿蝕刻光阻以露出奈米線頂部，續以電子槍蒸鍍系統鍍上氧化銦錫，並經退火10分鐘以形成透明電極。製作完成後的電池元件以掃描式電子顯微鏡觀察表面形貌，並以太陽光能模擬系統量測，確定在矽基板上成長之砷化鎵奈米線可組裝成太陽能電池。

關鍵字

砷化鎵 ； HASH(0x1f1dfd20) ； 奈米線 ； HASH(0x1f1dfe60) ； 奈米線太陽能電池

並列摘要

In comparison with silicon solar cells, the GaAs cells offer the advantage of having high absorption coefficient and direct bandgap. In particular, the GaAs cells in the form of coaxial nanowires offer the further advantage of having optimal light absorption and enhanced carrier collection, and thus have great potential to implement advanced high efficiency schemes.
Synthesis and fabrication of GaAs nanowire solar cells on GaAs substrates has been widely investigated. However, epitaxial growth of GaAs nanowires on Si substrates has been rarely reported. In this work, we report the realization of GaAs nanowire solar cells on Si substrates. Synthesis of p-n coaxial GaAs nanowires was achieved by means of the Au-catalyzed vapour-liquid-solid (VLS) method by MBE using Be and Si as the p-type and n-type dopants, respectively. In device process, photoresist was first spin coated on the nanowire sample, followed by oxygen plasma etch to remove the photoresist from the tip of the nanowires. Indium tin oxide was then deposited on top of the nanowires by e-beam evaporation and annealed for 10 min to form transparent contact to the sample surface. Morphology of the devices was analyzed by scanning electron microscopy and I-V characteristics were measured using a solar simulation system. The results reveal a good progress for the use of GaAs nanowires in the fabrication of third generation solar cells on Si substrates.

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