臺灣博碩士論文加值系統

在本論文中， 研究矽化鋅溶膠在擴散過程中之摻雜效應而且形成P+層應用於砷化鎵太陽能電池研製也被研究。利用熱爐管擴散鋅到砷化鎵基板形成界面。可以發現利用100奈米的二氧化矽覆蓋在砷化鎵基版上，它可以在高溫處理中減少砷化鎵基版表面組態的傷害而且在表面上的殘留溶劑比較容易清潔。另外，利用射頻濺鍍機沉積50奈米之銦錫氧化薄膜在砷化鎵太陽能電池上當作前面電極。我們可以發現到經由高溫氮回火後，會形成高透明度之銦錫氧化薄膜。然而經由高溫氧回火500度後，在波長460 nm時，穿透率可提高至82.5 %。另一方面，利用熱蒸鍍機沉積100奈米金鍺鎳之合金薄膜在n型的砷化鎵上當作背電極。我們可以發現到剛沉積完成的金鍺鎳之合金薄膜在n型之砷化鎵上會呈現蕭基接觸的現象。然而，經由高溫氧回火後，金鍺鎳之合金薄膜將會和n型之砷化鎵形成良好的歐姆接觸。此外，固定在六十分鐘探討擴散砷化鎵之不同擴散溫度。隨著擴散溫度增加，則表面之電洞濃度從每平方公分3.13x1015增加到1016，而溫度則從700度增加到800度。其電洞會隨著擴散溫度之增加而下降。擴散溫度在700度、750度、800度時，其砷化鎵太陽能電池之效率分別為2.611%、4.089%、3.892%。然而，我們將溫度固定在750度而不同擴散時間。隨著擴散時間增加，則表面之電洞濃度從每平方公分6.47x1015降低到4.11x1015，而時間則從15分鐘增加到120分鐘。這可能是因為在長時間高溫處理下，砷化鎵之基板表面的鋅化物會被蒸發。而且也可以發現到擴散深度會隨著擴散時間加增而增加。在30分鐘之擴散時間的效率是最好的。但是效率只有5.428%，這是因為砷化鎵表面的高反射造成光電轉化效率非常低。

In this thesis, the effect of spin-on Znicsilicafilm dopant content on the diffusion process and formation of p+ layer was applied to fabricate the GaAs solar cells were also investigated. The p-n junction was formed by thermal furnace from diffusion of Znic into the GaAs substrate. It can be found that the GaAs substrate has to be covered by 100nm thickness of SiO2 layer. It can reduce to the GaAs substrate surface morphology damaged during a high temperature treatment and easier cleaned residual solvate on surface. In addition, 50nm-thick ITO films were deposited on the GaAs solar cell serve as front electrode by RF sputtering. It was found hat highly transparent ITO after N2 annealing. With an incident wavelength of 460 nm, it was found that transmittance of 500oC-annealed ITO films was 82.5 %. In the other hand, 100nm-thick Au-Ge-Ni films were deposited on the n-GaAs serve as back electrode by thermal evaporator. It was also found that as-deposited Au-Ge-Ni formed Schottky contact on n-GaAs. However, good ohmic contacts were formed between the Au-Ge-Ni films and the n-GaAs with 450oC-annealed.
Further, a study of the GaAs substrate was diffused by different diffusion temperature for 60 min. With increased diffusion temperature, the surface hole concentration was found to increase from 3.13x1015 cm-2 at 700℃ to 1016 cm-2 at 800℃. The hole mobility was found to decrease with an increase in diffusion temperature. It can be found that the diffusion temperature of 700 oC、750 oC and 800 oC, the efficiency of the GaAs solar cells were 2.611 %, 4.089 % and 3.892 %, respectively. And then we continued to experimental with different diffusion time for temperature keep 750 oC. With increased diffusion time, the surface hole concentration was found to decrease from 6.47x1014 cm-2 for 15min to 4.11x1014 cm-2 for 120min. This may be due to the Zinc of the GaAs substrate surface was evaporated during long time and high temperature treatment. And then it can also be found that diffusion depth was increased with increase of diffusion time. The efficiency of the diffusion time of 30 min is the best. But the efficiency is only 5.428%, this is because of high reflection loss of GaAs surface resulted a lower IPCE.

Abstract (in Chinese) -----------------------------------------------------------I
Abstract (in English) ----------------------------------------------------------III
Contents --------------------------------------------------------------------------V
Table Captions ----------------------------------------------------------------VII
Figure Captions --------------------------------------------------------------VIII


Chapter 1 Introduction 1
1.1. Background 1
1.2. Motivation 2
1.3. Organization 3
Chapter 2 Fabrication System and the Theorem of Solar Cells 10
2.1. Fabrication System 10
2.1.1. RF Sputtering System 10
2.1.2. Diffusion Furnace System 11
2.1.3. Hall Measurement System 12
2.1.4. Secondary Ions Mass Spectrometer System 13
2.1.5. Atomic Force Microscopes 13
2.1.6. Spreading Resistance Profiling 13
2.1.7. Solar Cells Measurement System 16
2.2. Theorem Of The Solar Cells 17
2.2.1. The solar spectrum 17
2.2.2. The Mechanism of Photovoltaic 17
2.2.3. Efficiency and Equivalent Circuit Model 19
2.2.4. Light trapping 20
Chapter 3 Experimental Procedure 33
Chapter 4 Results and Discussion 37
4.1. Compared with SiO2 and without SiO2 layer 37
4.1.1. SEM Analysis of the diffused layer Surface Morphology 37
4.1.2. Analysis of Hall measurement 37
4.1.3. Analysis of SIMS 38
4.1.4. The Transparency Analysis of ITO films 38
4.1.5. The Electrical properties Analysis of metal/n-GaAs 38
4.1.6. Analysis of solar cell measurement 39
4.2. The effect of diffusion temperature 40
4.2.1 SEM Analysis of the diffused layer Surface Morphology 40
4.2.2 Analysis of Hall measurement 41
4.2.3. Analysis of SIMS 41
4.2.4. Analysis of solar cell measurement 42
4.3. The effect of diffusion time 43
4.3.1 SEM Analysis of the diffused layer Surface Morphology 43
4.3.2 Analysis of Hall measurement 43
4.3.3. Analysis of SIMS 43
4.3.4. Analysis of solar cell measurement 44
Chapter 5 Conclusion and Future Work 67
5.1. Conclusion 67
5.2. Future Work 69
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