砷化鎵奈米柱陣列太陽能電池之光電模擬

Abstract

奈米柱陣列太陽能電池擁有獨特的抗反射和光侷限特性，以及特殊的輻射狀接面設計，也已經有許多相關的理論分析與模擬。然而，過往的奈米柱太陽能電池的電性模擬中，連續方程式中電子電洞對因光照而產生的分布往往只以和平面結構一樣的比爾-朗伯定律（Beer–Lambert law）計算。在這篇論文中，我們使用COMSOL Multiphysics的低頻模組及半導體模組分別建立了砷化鎵奈米柱太陽能電池的光、電模型，呈現光電耦合的太陽能電池數值分析結果。在光學模擬中，透過光散射及光電流的分析，得到最佳化的奈米柱陣列結構；在電性模擬中，透過電流電壓曲線及電場分布的分析，得到垂直接面與輻射接面兩種奈米柱太陽能電池所需的摻雜濃度與接面設計。此外，因為極高的表面對體積的比例，表面缺陷及三五族材料的高介面能態會對太陽能電池效率產生極大的影響，我們呈現不同的表面複合速率與介面能障對砷化鎵奈米柱太陽能電池影響的數值分析。最後，根據我們的模擬結果，經過表面處理的深化鎵奈米柱陣列太陽能電池能達到20%的光電轉換效率。

There have been many theoretical analyses and simulations about the anti-reflection and light-trapping properties of nanorod array solar cells, as well as the unique radial junction design. However, in continuity equations of electrical simulations, generation term of nanorod solar cells used to be approximated by Beer Lambert law same as the planar counterpart. In this work, we build the optical and electrical models of GaAs nanorod array solar cells by radio frequency and semiconductor module on COMSOL Multiphysics® software, and present the coupled optical and electrical results. In optical simulations, optimal nanorod array arrangement was obtained through light scattering and photocurrent analyses. In electrical simulations, doping and junction design were optimized through studies of current-voltage characteristics and electric field distributions. In addition, due to the high surface-to-volume ratio, surface defects and high surface states of III-V semiconductor interface would largely influence solar cells’ performances. We performed the numerical study on the influence of surface recombination velocity and interface barrier height. Finally, according to our simulation results, GaAs nanorod array solar cells can achieve 20% power conversion efficiency with good sidewall passivation.