本論文主要探討元件的吸收波長、MQW的barrier厚度與摻雜濃度對
垂直式太陽能電池特性的影響，並觀察以Si基板替換藍寶石基板在高倍
率太陽光照射下，能否改善轉換效率下降的問題，最後透過額外附加一
層紫外光吸收層，嘗試增加元件對太陽光的使用效率。
(1)變吸收波長試片:經過模擬光源量測，吸收波段越長可產生光電流越
多，雖然因為能隙較小進而使得開路電壓下降，轉換效率仍以吸收波段
較長者為佳。垂直式結構以Si基板替換藍寶石基板在300倍太陽光照射下，
足以抵抗熱效應進而提升元件表現。
(2)變barrier層厚度、摻雜濃度試片:在不影響磊晶品質情況下，barrier
層厚度越薄越好;摻雜濃度則需適中，摻雜濃度過低使得barrier層導電
特性不佳，過多則讓磊晶品質下降，都會降低轉換效率。
(3)附加紫外光吸收層試片:經由EQE量測發現，附加層並沒有增加紫外光
使用效率，推測是因為附加層與量測電極中間之，使得附加層轉換出的
電子電洞無法輸出。

In this thesis, vertical InGaN-based solar cells were fabricated by wafer bonding technique, and the thermally resistive sapphire substrates were replaced by the Si substrate with high thermal conductivity . We modulated the In composition of vertical InGaN-based solar cells, altered the thickness and Si doping level of quantum barrier (QB) in vertical InGaN-based solar cells multiple quantum well (MQW), and we made an additional ultraviolet ligh MQW above the device structures. We, then, investigated the optical and electrical characteristics for these cells, trying to find out the better way for the cells. For the modulation of In composition of vertical InGaN-based solar cells. The typical peak wavelength of the electroluminescence spectra taken from the InGaN/GaN/Si solar cells was approximately 400nm, 455nm, and 525 nm. The wavelength of 525nm cells had better performance because of additional light absorption. On the other side, the vertical solar cells did not show degradation in power conversion efficiency (PCE) even when the solar concentrations were increased to 300 suns. Comparing to low Si doping level(~3×1017 cm-3), high doping level(~3×1018 cm-3) led to poor material quality, the shunt resistance (Rsh) decreased, and the undoped (~1×1016 cm-3)barrier lead to high series resistance (Rs). Besides, under the premise that all cells had same doping level, the reduction in barrier thickness resulted in the increase of the PCE. This condition can be attributed to the thinner barrier thickness decreasing the Rs and increasing the short circuit current. The cells with additional ultraviolet ligh MQW above the device structures did not showing improvement in power conversion efficiency, because the n+-GaN layer and strain release layer thickness were too high. Even though there still remained weak ultraviolet ligh absorbed by active layer, the carriers would recombine with the defect

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