Type-II 量子環位置對太陽能電池的影響

Abstract

本論文中，type-II 量子環被應用在太陽能電池中，用來增加紅外光的吸收，並探討量子環在不同磊晶層對太陽能電池的影響。在這次實驗中，一共有三片具有量子環結構的磊晶片(p-QR,n-QR,i-QR)和一片基準片被製程並量測，就結果而言i-QR表現最佳，但i-QR對紅外線的反應極弱，代表量子環的表現極差，主要原因可能發生在雙倍的量子環磊晶上。相較於n-QR，p-QR 有較佳的理想因子和較強的紅外線反應，主要原因可能是，p-QR的量子環比較靠近元件表面，因此能吸收較強的光，但也因為此原因，p-QR的量子環有機會吸收到可見光的部分，因此會降低紅外光的轉換效率，最後就實驗結果，我們發現，P型參雜的量子環再主動層中，會造成元件的填充因數明顯低落。如果能將上述問題解決，我們相信量子環能明顯提升太陽能電池的效率。

In this thesis, type-II quantum rings are applied in the solar cell to provide possible enhanced absorption in the infrared region. The main focus is the positioning of the quantum rings among the epitaxial layers. Three wafers (p-QR, n-QR and i-QR) with quantum rings and one reference were processed and measured. Although the i-QR performs better than other quantum rings solar cells but the i-QR show low absorption in infrared band, which means the poor performance of quantum rings. Compared with n-QR, p-QR is good at the ideality factor and infrared response. From the experimental results, the p-QR has stronger IR response due to its position close to the top, but at the same time, this position can absorb visible photons as well and the overall EQE can be deteriorated. On the other hand, n-QR design (embedded p-type QR in the active region) can damage the fill factor. The i-QR might be vulnerable due to the doubled quantum ring growth, which can be observed in the poor IR response. We believe that the type-II quantum rings can be a great candidate for boosting up the solar cell efficiency if the structural design is optimized.