| 摘要: | 這份研究主要是透過電漿輔助化學氣沉積法以及氯化物前驅物；四氯化鍺、四氯化矽，獨立發展製備鍺/矽/玻璃基板材料的堆疊型太陽能電池的前級與後級，並期望在未來發展將兩層薄膜整合的技術。
選用的玻璃基板材料種類分別有無鹼玻璃、石英玻璃、氧化銦錫層導電玻璃，並各自觀察到在升降溫過程中，薄膜受到應力影響而產生皺摺、龜裂進而導致剝落的形變。從450°C降至室溫的過程中，鍺/石英玻璃會產生龜裂的形變，發生的臨界厚度約為1 μm，而鍺/氧化銦錫層導電玻璃會產生皺摺形變，發生在薄膜較薄(小於200 nm)或鍍膜溫度較低的時候，只有鍺/無鹼玻璃在厚度2 μm內都沒有觀察到任何的形變產生。
從鍺沉積在三種基板上的XRD圖譜來看，觀察到鍺在(220)晶面有較為強烈的訊號。從拉曼光譜分析，隨著鍺薄膜厚度增加到1μm，薄膜累積的拉伸應變(Tensile strain)會自發性釋放，從295 cm-1回歸到接近300.9 cm-1的位置。
矽薄膜在三種玻璃上同樣也有應變導致的形變問題，沉積結束後的降溫過程中，矽薄膜/無鹼玻璃會產生皺褶的形變而剝落，發生的臨界厚度約為薄膜厚度小於200 nm的時候，此外，在熱退火時由室溫升溫至450°C，矽薄膜/石英玻璃會產生皺摺形變而剝落，而矽薄膜/氧化銦錫玻璃上至少在1 μm內都沒有觀察到任何的形變產生。
此外還發展了原味摻雜鎵原子的技術，透過使用三氯化鎵前驅物，在鍺薄膜沉積的同時進行摻雜，量測到最低的電阻率可達0.001Ω·cm。
本研究中發展在玻璃基板上的薄膜型太陽能電池，還未能夠觀察到可信的轉換效率，僅有接近儀器誤差值的10-6 %。用四點探針量測沉積完尚未佈植的純鍺薄膜的電阻率過低，僅有0.12 Ω·cm，推測在鍍膜過程中有意外的雜質摻入。暫時轉往發展鍺/N型矽基板的太陽能電池時，成功的得到6.2%的轉換效率，短路電流值為54.2 mA/cm2、開路電壓為310 mV，填充因子為38.2%。
;This study primarily employs plasma-enhanced chemical vapor deposition (PECVD) and chloride precursors (germanium tetrachloride and silicon tetrachloride) to independently develop the front and rear layers of germanium/silicon/glass-based tandem solar cells. The goal is to integrate these two thin films in the future.
The types of glass substrates used include alkali-free glass, quartz glass, and indium tin oxide (ITO) conductive glass. During the heating and cooling process, stress-induced wrinkles, cracks, and subsequent peeling deformations were observed in the films. When cooling from 450°C to room temperature, the germanium/quartz glass exhibited cracking deformation at a critical thickness of about 1 μm. The germanium/ITO conductive glass showed wrinkling deformation when the film was thinner (less than 200 nm) or when the deposition temperature was lower. No deformation was observed in the germanium/alkali-free glass for thicknesses up to 2 μm.
XRD patterns of germanium deposited on the three substrates showed a strong signal on the (220) crystal plane. Raman spectroscopy analysis indicated that as the thickness of the germanium film increased to 1 μm, the accumulated tensile strain in the film spontaneously released, shifting from 295 cm-1 to nearly 300.9 cm-1.
Silicon films on the three types of glass also exhibited strain-induced deformation issues. During the cooling process after deposition, silicon films on alkali-free glass showed wrinkling deformation and peeling at a critical thickness of less than 200 nm. Additionally, during thermal annealing from room temperature to 450°C, silicon films on quartz glass showed wrinkling deformation and peeling, while no deformation was observed for silicon films on ITO glass up to a thickness of 1 μm.
Furthermore, a technique for in-situ gallium doping was developed. Using gallium trichloride as a precursor, doping was carried out simultaneously during the deposition of the germanium film, achieving a minimum resistivity of 0.001 Ω·cm.
In this study, thin-film solar cells developed on glass substrates did not yet show reliable conversion efficiency, only achieving a value close to the instrument′s error margin of 10^-6%. The resistivity of the pure germanium film measured with a four-point probe was as low as 0.12 Ω·cm, suggesting accidental impurity incorporation during the deposition process. Temporarily shifting focus to developing germanium/N-type silicon substrate solar cells resulted in a conversion efficiency of 6.2%, with a short-circuit current density of 54.2 mA/cm², an open-circuit voltage of 310 mV, and a fill factor of 38.2%. |
