砷化銦量子盤/線耦合砷化鋁鎵/砷化鎵量子井應用於中間帶太陽能電池

InAs Quantum Disk/Wire with AlGaAs/GaAs Quantum Well Coupling Effects Applied to the Intermediate Band Solar Cell

古運承(Yun-Cheng Ku)

指導教授 ： 郭茂坤

共同指導教授 ： 林資榕(Tzy-Rong Lin)

國立臺灣大學/工學院/應用力學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602940

摘要

本文旨在研究砷化鋁鎵與砷化鎵量子井對砷化銦量子盤及量子線結構的光電性質影響。文中以線彈性力學與k·p理論，配合有限元素法估算量子井厚度、材料濃度對於量子結構的光電性質之效應，並以載子控制方程式計算含有中間帶特性的太陽能電池之轉換效率。
研究發現砷化鋁鎵與砷化鎵量子井對於不同尺寸大小的量子盤之間的耦合強度會有不同的影響。對耦合效應太強的量子盤結構，砷化鋁鎵與砷化鎵量子井的勢能侷限，對於其光電性質影響不大，然而對縱向耦合性較弱的量子盤，量子井的勢能變化將增強電子的在側向的耦合性質，進而影響中間帶至導電帶的吸收係數範圍。而量子井對於砷化銦量子線方向的週期性勢能影響，造成量子線方向上的連續能帶，會因為量子井的變化產生分裂，形成耦合效應強烈的中間帶，使得中間帶至導電帶的吸收係數由量子線與量子井特性組成，促成有較大面積的吸收頻譜。而中間帶的帶寬將會受到量子井的性質耦合至不同的量子線能階中，而產生不同的帶寬變化。
本文目的研究量子結構帶入太陽能電池中，與砷化鎵太陽能電池之比較。含中間帶的量子結構可多利用到低於材料能隙能量的光子，進而轉換成少數載子，相較單能隙的砷化鎵太陽能電池的短路電流15.29 (mA/cm2)，其最大的短路電流可以到34.13 (mA/cm2)；而轉換效率上，砷化鎵太陽能電池為9.45 %，而量子結構太陽能電池最好的轉換效率為21.64 %。

關鍵字

量子點 ； 量子線 ； 量子井 ； 有限元素法 ； 中間帶太陽能電池

並列摘要

This thesis studies the optical properties of InAs quantum structure, including InAs quantum disk and quantum wire with AlGaAs/GaAs quantum well. A model based on theory of linear elasticity and k p theory is developed with the aid of finite-element method to analyze effects of quantum system band structure and absorption coefficient.
Numerical results show that effects of AlGaAs/GaAs quantum well change with sizes of quantum disk. When the coupling from neighboring quantum disks is strong, effects of AlGaAs/GaAs quantum well is weak and the structure of optical and electrical properties has only slightly change. When the coupling from neighboring quantum disks is weak, the periodic potential is huge barrier for disks coupling effects in the direction of the well. This potential barrier lets elections enhance in side direction coupling. The quantum well is periodic potential for the direction of quantum wire, the potential change let continuous energy state separate intermediate band. This coupling effect is strong and absorption spectrum of intermediate band to conduction band transitions is broad.
The quantum structures with intermediate band have abilities to use photons below the material band gap. The best short-circuit current of the intermediate band solar cell (IBSC) structure is 34.13 (mA/cm2) which is much great than the GaAs solar cell 15.29 (mA/cm2). Moreover, the best conversion efficiency of IBSC can be achieved to 21.64 %.

並列關鍵字

quantum dot ； quantum wire ； quantum well ； finite element method ； intermediate band solar cell

參考文獻

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