奈米級 GaAs 太陽能電池之模擬

Abstract

我們在GaAs奈米柱太陽能電池的側壁加入一層SiO2作為鈍化層進行對光學及電性模組之模擬。在光學模組模擬中，考慮SiO2層的高度和厚度，觀察在不同的高度和厚度下的吸收、反射及穿透來了解SiO2層對光學特性的影響，並在模擬中計算了奈米柱的generation profile並作為在電性模擬中的generation rate進行電性模擬，在電性模擬中，討論SiO2對太陽能電池JV的影響，頂部、側壁以及底部的金屬接觸均視為理想歐姆接觸來忽略金屬和半導體之間的相對電阻，在理想歐姆接觸的情況，加入SiO2層後能提高整體的電流電壓特性曲線來達到更好的Jsc，但在較低高度的SiO2層下Jsc的變化浮動，無法穩定提升Jsc，而在較高高度下，鈍化層的影響慢慢下降使得Jsc下降。對於厚度的影響，鈍化層需要一定的厚度才能有效的提高Jsc。而由於奈米柱太陽能電池具有較大的surface-to-volume ratio，因此表面複合也是影響太陽能電池性能的重要因素。

We simulate both of optical and electrical modules into GaAs nanorod solar cell with SiO2 side-contact as the passivation of sidewall. In optical simulation, consider the height and thickness of SiO2 layer. Absorption, reflection and transmission were observed to know the influence of the SiO2 side-contact layer in the optical characteristic. Among this, also compute the total generation profile in nanorod which we assume as the interpolation of the generation rate into electrical simulation. In electrical simulation, study the height and thickness dependence of SiO2 contact layer. The all contact (top, side and bottom contact) are assumed as ideal contact which can ignore the relative resistance between metal and semiconductor connected. Under the set up above, SiO2 layer can enhance the current-voltage characteristic to higher Jsc. At short height of SiO2, the enhancement is probably unstable that Jsc moves up and down. while at tall height of SiO2 layer, the influence of passivation layer becomes lower that lead Jsc beginning decrease. In thickness dependence, the layer must be thick enough to obtain better performance efficiently. Since the nanorod solar cells have larger surface-to-volume ratio, surface recombination is an important factor which heavily influence the performance of nanoscale solar cells.