以金屬層前驅物硒化法製備硒化銅銦鎵薄膜太陽能電池之研究

Abstract

本論文針對CIGS薄膜太陽能電池進行研究。先以直流濺鍍法沉積鉬背電極，探討不同直流功率與製程壓力對鉬背電極之影響。研究結果發現，改變製程壓力鉬薄膜片電阻值、結構、表面粗糙度皆有明顯的變化，在高直流功率和低製程壓力的條件下有較佳的導電性，經計算後最佳電阻率為1.3×10-5Ω-cm，符合做為CIGS薄膜太陽能電池之需求。理論而言，鉬薄膜在低製程壓力時殘留應力應為壓應力型態，但在本研究中因較高直功率的因素而產生原子珠擊效應，導致鉬薄膜在低製程壓力時呈現出張應力的型態。經由附著力測試後，僅有殘留應力為壓力型態出現剝落的情況。改變直流功率對鉬背電極薄膜的反射率並無太大之影響。但改變製程壓力則得到明顯的變化，當製程壓力1mTorr時約有70 %的反射率，但提高製程壓力到10 mTorr時，因薄膜的平均粗糙度變大，導致反射率則降至35%。此外，以金屬前驅物層硒化法來製備CIGS吸收層，使用的靶材為Cu0.75Ga0.25靶與銦靶，以直流濺鍍的方式鍍製CIG金屬層前驅物，藉由改變銦靶鍍膜時間來調整Cu/(In+Ga) ratio。接著，以RTP硒化的方式使CIG金屬層前驅物與硒金屬層反應成為CIGS吸收層，並觀察不同Cu/(In+Ga) ratio(0.75、0.95、1.15)對CIGS吸收層特性之影響。研究結果發現，以Cu/(In+Ga) ratio=0.95 的CIGS吸收層做成太陽能電池元件，經照光後量測其I-V曲線，當元件照光面積=1.19 cm2，可得轉換效率(η)= 6.96 %之CIGS薄膜太陽能電池，其開路電壓(Voc)=537 mV、短路電流密度(Jsc)=22.90 mA/cm2、填充因子(FF)= 47.55%。

This thesis focuses on CIGS thin film solar cells. First, the molybdenum back electrode depositioned by DC sputtering and explore the different DC power and process pressure of molybdenum back electrode. The results showed that the change process pressure molybdenum thin film sheet resistance value, structure, surface roughness significantly better electrical conductivity changes in conditions of high DC power and low process pressure was calculated resistance 1.3 × 10-5Ω-cm, in line with demand as CIGS thin film solar cells. Theory, the molybdenum film residual stress in the low process pressure should be as stress patterns, but in this study due to higher direct power factor arising from atomic beads hit effect, leading to the molybdenum film showing a tensile stress in the low process pressure pattern. Through the adhesion test, only the residual stress of the pressure type peeling off. Change the DC power reflectivity is not too much of the influence of molybdenum back electrode film. Change process pressure, but significant changes, when the process pressure 1mTorr about 70 % reflectivity, but to improve the process pressure to 10 mTorr, the average roughness of the film lead reflectivity to 35 %. In addition to the fund is a precursor layer of selenium method to prepare the CIGS absorber layer, the use of target Cu0.75Ga0.25 target and indium target, DC sputtering coated the CIG metal precursor, by changing the indium target deposition time to adjust the Cu / (In + Ga) ratio. Then, the RTP selenide way to make the CIG metal precursors with selenium metal reactions become the CIGS absorber layer. The different Cu / (In + Ga) ratio (0.75, 0.95, 1.15) CIGS absorption layer characteristics. The study found that the absorbing layer made of Cu / (In + Ga) ratio = 0.95 CIGS solar cells, according to light after the amount of measured IV curve, when the components according to the light area = 1.19 cm2 conversion efficiency (η) = 6.96 % of the CIGS thin film solar cells, the open circuit voltage(Voc) = 537 mV, short circuit current density (Jsc) = 22.90 mA/cm2, fill factor(FF) = 47.55 %.