- 學位論文
使用固體鋅擴散製程於磷化銦太陽能電池之研究
Fabrication of InP-based Solar Cell Using Solid Source Zinc Diffusion Process
摘要
鋅擴散已被廣泛使用在Ⅲ-Ⅴ化合物半導體，而在元件製程方面鋅擴散是一相當關鍵的步驟，因為P-N接面的深度、陡度、均勻度、及電洞濃度均由鋅擴散製程決定，上述這些參數p-n決定元件的特性、良率等。本實驗利用固體鋅(Zn3P2)擴散源及快速熱退火的方式(Solid source/ RTA) 建立鋅擴散製程參數及應用於太陽能電池製作。 本實驗在不同磊晶結構以N型為主的磷化銦基板上，以擴散溫度550℃擴散時間10分鐘，擴散形成 p+型區域，然後再以600℃ 時間10秒鐘的快速熱退火活化(Activation)處理，將電洞濃度提昇至≧3×1018cm-3。經由ECV載子濃度分佈量測其p-n之接面陡峭度與擴散深度。 利用Solid source/Rapid Thermal Annealing技術，將鋅(Zn)以熱擴散進入n-/n+-InP基板及n-/i/n+-InP基板形成p+-n接面，並且製作完成 p+/n–-n+- InP與p+/n–-i-n+- InP太陽能電池。我們量測其二極體p-n接面暗特性，獲得逆向飽和電流(I0)與理想因子(Ideality factor，n)參數；另外，在AM 1.5G、25℃條件下，量測太陽能電池的特性參數:開路電壓(Open circuit voltages, Voc)、短路電流密度(Short circuit current density, Jsc)、填充因子(Fill factor，FF)與轉換效率(Conversion efficiency，η)。 最後，我們成功的製作出p+-n以N型磷化銦為基板的太陽能電池，所得到的雙異質磊晶結構磷化銦/砷化銦鎵/磷化銦太陽能電池在未加上抗反射膜前，短路電流密度(Jsc)為34.72 mA/cm2，而轉換效率(η)為7.62%，經由電子槍蒸鍍系統蒸鍍雙層抗反射膜技術來成長抗反射膜，所得到的短路電流密度45.76mA/cm2而轉換效率為10.29%。；磊晶片磷化銦太陽能電池在未加上抗反射膜前，所得到的短路電流密度為26.23 mA/cm2而轉換效率為8.41%，最後經由蒸鍍雙層抗反射膜技術成長抗反射膜後，所得到的短路電流密度34.88mA/cm2而轉換效率為11.64%。另外，當電極線寬為27μm，間距為590μm時，能夠滿足最佳化電極設計的要求。
並列摘要
The Zn diffusion using a solid source is a relatively simple and reproducible method for mass production of InP-base optoelectronic devices. In this study, we use the Zn3P2 compounds as diffusion source for diffusion in n-type InP surface in a semi-closed ampoule. Diffusion was performed in the rapid thermal anneal (RTA) system under the nitrogen ambient. Finally, the wafer were activated additionally at 600℃ for 10 sec by the same RTA system to achieve a high degree of activation. This thesis is study using solid source (Zn3P2) and RTA diffusion technique for a p-n junction InP solar cell fabricated process. Firstly, the zinc (Zn) diffusion source was diffused in the hetrojunction InP wafer (n-/i/n+-InP) and epi-n-type single crystal InP wafer (n-/n+-InP) annealing at 550 ° C and 10 minutes for diffusion and to form a p + -n junction. The ideality factor of fabricating n-/i/n+-InP and n-/n+-InP pn diode are 1.83 and 1.94, respectively. And then, the InP solar cells evaporated with TiO2 of 59.2nm and SiO2 of 95.4nm double anti-reflective layer were characterization. Finally, we use Solid source/RTA process to fabricate the InP solar cells which the Zn impurities were thermally diffusing into hetrojunction InP (InP/InGaAs/InP) and n-type epitaxial InP (n-/n+-InP) to form P+n junction. And then, cells area are 0.1296cm2 under AM1.5G, 25℃ conditions, the performances of fabricated hetrojunction InP (InP/InGaAs/InP) and n-type epitaxial InP (n-/n+-InP) solar cell were measured and analyzed. In the absence of AR-Coating, the hetrojunction InP open circuit voltage Voc of 0.35V, short-circuit current density Jsc of 34.72mA/cm2, and η of 7.61% are presented；with double layer AR-coating, Voc of 0.35V, Jsc of 45.75mA/cm2, and η increased to 35.21% are obtained; more over, the (n-/n+-InP) solar cell in the absence of AR-Coating, open circuit voltage Voc of 0.75V, short-circuit current density Jsc of 26.23mA/cm2, and η of 8.41% are presented；with double layer AR coating, Voc of 0.75V, Jsc of 34.87mA/cm2, and η increased to 38.4%.