利用濕式蝕刻法粗糙化氧化鋅掺鋁薄膜 特性分析

Characterization of Textured Aluminum Doped Zinc Oxide Films by Wet Etching

李恒旭(Heng-Hsu Li)

指導教授 ： 李道聖

共同指導教授 ： 張慎周(Shang-Chou Chang)

崑山科技大學/工程學院/電機工程研究所/碩士(2009年)

摘要

本研究主要為利用濕式蝕刻法使氧化鋅掺鋁薄膜產生粗糙化結構，對於應用在太陽能電池中當透明電極使用時，使入射光通過太陽電池元件表面時，降低入射光線的反射率，使更多入射光能通過太陽能電池中的吸收層，提升太陽電池的轉換效率。
實驗中以酸性的HCl與鹼性的KOH兩種溶液作為蝕刻製程中的蝕刻液，蝕刻試片則為連續式濺鍍機台於不同基板溫度與不同製程氣體的製程條件下濺鍍所得的四組試片(A50、A150、AH50、AH150)，而四組試片經由不同蝕刻參數蝕刻後所得的試片由光譜儀、掃描式電子顯微鏡及四點探針分析薄膜經蝕刻後的特性變化。
由實驗後結果得知經KOH溶液蝕刻後薄膜的光學特性普遍比由HCl溶液蝕刻後獲得更佳的改善，其中A50這組試片經由33wt%的KOH溶液蝕刻30秒後，平均穿透率可由81.98%增加為83.15%，且平均反射率由16.59%下降至9.05%，相對於原來的反射率，下降幅度達45%。另外，A150與AH50這兩組試片經5wt%的KOH溶液蝕刻100秒後，薄膜表面原本所存在大量的島狀物與晶粒大小明顯差異的情形皆獲得改善，且平均穿透率分別由87.23%與87.31%增加至90.7%與90.06%，平均反射率則分別由12.43%與12.78%下降至7.79%與10.78%。而AH150這組試片經33wt%的KOH溶液蝕刻30秒後，平均穿透率由原來的90.39%增加至96.38%，相對於原來的穿透率，成長幅度達6%，此組試片也為所有蝕刻後試片中平均穿透率增加最多者，而平均反射率也由12.98%下降至9.58%。由上述的光學性質變化中可得知，經由濕式蝕刻過程後的氧化鋅掺鋁薄膜確實能有效改善薄膜的光學特性，對於應用於太陽電池中當透明電極使用時，能使更多入射光通過元件表面而進入吸收層內，幫助提升太陽電池的轉換效率。

關鍵字

濕蝕刻 ； 氧化鋅掺鋁薄膜

並列摘要

This project provides an overview of surface texturing of aluminum doped zinc oxide (AZO) films by wet etching. For thin films solar cell application, the light passed through solar cells reduced reflectance to permeate into absorb layer of solar cells improve the conversion efficiencies when using solar cells as transparent electrode.
In this work, acidic (HCI) and alkaline solutions (KOH) were used as etching solutions from the etching behavior. Four sample AZO films (A50、A150、AH50、AH150) were produced from four different recipe with in-line sputtering. Four sample films were separately etched with different etching solution concentration and time. The optical transmittance of the etched samples were measured by a spectrophotometer, scanning electron microscopy (SEM) and four-point probe.
Optical properties of films etched by KOH solution are better than those etched by HCl. The film A50 was etched for 30 sec by 33wt% KOH solution. The average transmittance 81.98% was increased to 83.15% while the average reflectance 16.59% was reduced to 9.05%. Compared with the original reflectance, 45% decrece is accomplished. In addition, the films of A150 and AH50 were etched for 100 sec by a 5wt% KOH solution. The existing defects on the surface of thin films were getting improved. Average transmittances of 87.23% and 87.32% were increased to 90.7% and 90.06%, respectively and average reflectance 12.43% and 12.78% was reduced to 7.79% and 10.78%. The film of AH150 was etched for 30 sec by a 33wt% KOH solution. Average transmittance 90.39% was increased to 96.38%. Compared with the original reflectance, 6% increase is accomplished. AH150 film is the most improved transmittance of all films and the average reflectance 12.98% was reduced to 9.58%. As above mentioned, it could be improved the optics characterization of films efficiently by textured aluminium doped zinc oxide films by wet etching. Using solar cells as transparent electrode enables the light passed through solar cells and reduceds reflectance to permeate into absorb layer of solar cells and improve conversion efficiencies of solar cells.

並列關鍵字

wet etching ； aluminum doped zinc oxide films

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