近年來氮化鎵材料已成為製作藍光發光二極體的主流且快速的發展。另一方面，自從氮化銦能隙更正後，發現以能隙為紫外光波長的氮化鎵(3.4eV)與紅外光波長的氮化銦(0.7eV)組成的氮化銦鎵，能組合成幾乎涵蓋整個太陽光譜(0.7-3.9eV)的多接面太陽能電池。因此本實驗的目標為在一片磊晶片上同時製作出太陽能電池與發光二極體兩種元件並積體化，使元件在光照下將光能轉換成電能並直接供給發光二極體，發出藍光。在元件設計中要同時考慮製程與結構對兩種元件的影響，並做出積體化元件的最佳設計。
實驗中製作與比較不同結構與製程的元件，並量測發光二極體的I-V、L-I曲線與太陽能電池的I-V曲線，包括比較p型氮化鎵活化製程、以薄金屬製作電流擴散層，以ITO製作電流擴散層，對兩種元件的影響。量測結果發現p型氮化鎵與金屬電極之間有嚴重的蕭基接觸，造成發光二極體串聯電阻與啟動電壓增加，並且減低太陽能元件的光電流。藉由p型氮化鎵高溫活化製程提升p型氮化鎵濃度，可減低氮化鎵與金屬接面的蕭基接觸影響。以ITO製作電流擴散層的元件，由於製程中ITO與氮化鎵間已形成歐姆接觸，因此減低了發光二極體的串聯電阻與啟動電壓，加上ITO的電流擴散與高穿透率，總體上增加了發光二極體的光通量，並同時增加了太陽能電池的短路電流，兩種元件的效率都獲得顯著提升。因此評估以單一接面氮化鎵晶圓加上ITO電流擴散層做成太陽能電池與發光二極體積體化元件，每平方公分可產生0.25流明的光通量。

In recent years, GaN-based material has been rapidly developed for the manufacturing of blue LED. Moreover, it is newly considered as a candidate to make high-efficiency solar cells. Due to the discovery and correction of the number of InN bandgap energy, the whole solar spectrum which is 0.7-3.9eV can be covered by a multi-junction solar cell solely composed of GaN-based material with composition varied between GaN(3.4eV) and InN(0.7eV). Therefore, in this thesis we studied the feasibility to integrate solar cell and LED on the same wafer. Such device would transform solar power into electric power, and then drive LED directly to emit blue light.
In this research, we made devices of different processes and structures, including (1)p-doping activation process, (2)using thin metal as transparent conductive layer, and (3)using ITO as transparent conductive layer. The resulted LED's I-V and L-I curves and solar cell's I-V curve were measured and compared. We found there was serious Schottky contact between p-GaN and metal resulting in high turn-on voltage and series resistance for LED, and low photocurrent for solar cell. The p-doping activation process was proved to mitigate the Schottky contact problem by raising p-doping level. The device with ITO transparent conductive layer exhibited characteristic of Ohmic contact between GaN and ITO, plus good current spreading and high light transmission. As a result, LED's series resistance,turn-on voltage, and optical power were improved. In addition, it increased solar cell's short-circuit current. Therefore ITO transparent conductive layer improved both devices’ efficiency. It is evaluated that an integrated solar LED made of one-junction GaN-based material plus ITO transparent conductive layer would produce 0.25 Lumen per square centimeter in area.

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