臺灣博碩士論文加值系統

在本篇論文中，使用原子層化學氣相沉積(Atomic layer chemical deposition,簡稱ALD)，去鍍製不同高介電常數(High-κ)材料的薄膜當作太陽能電池的鈍化層。使用混合的方式，是想嘗試去找出能產生比Al2O3 更多固定電荷量或更好的界面狀態的混合比例。上述兩者特性都能有效地降低表面複合，並增加載子的生命週期，進而提昇開路電壓Voc ，其為影響太陽能電池效率的重要因素。
我們製作樣品分析之後，設定不同的鈍化條件，像是沒有任何的High-κ鈍化、只有正面有Al2O3、正反面有Al2O3、正面Al2O3背面混合Al2O3與HfO2以及正反面都使用HfO2。沒有High-κ鈍化的太陽能電池效率為5.637%、Jsc為31.394mA/cm2,、Voc為0.43V和 FF為0.417。但是使用Al2O3做正面鈍化效率可以改進到10.352%、Jsc為32.121mA/cm2,、Voc為0.51V和 FF為0.631。使用正反面Al2O3，則Voc可以改進到0.57V，效率有14.353%、Jsc和FF分別為35.624mA/cm2以及 0.707。而使用正面Al2O3背面使用Al2O3+HfO2時，Voc改進到0.58V、效率為14.957%、Jsc為36.31 mA/cm2、FF of 0.71。最後正反面都使用HfO2做為鈍化層，效率可以增加到15.542%、Voc改進到0.59V。High-κ材料鈍化層確實可以幫助太陽能電池提升Voc。

In this thesis, we investigated simple and compound high-κ materials deposited by ALD as passivation layer for silicon solar cells. Silicon solar cells were fabricated with different passivation conditions such as without any high-κ passivation, with passivation only in the front end with Al2O3 (8Å), with passivation using Al2O3 (8Å) at the front end as well as at the rear end, with passivation using Al2O3 (8Å) at the front end and using Al2O3+HfO2 (8Å) at the rear end and with passivation using HfO2 (8Å) at the front end as well as at the rear end. Solar cell efficiency obtained for the cell without any high-κ passivation was 5.637% with a Jsc of 31.394mA/cm2, Voc of 0.43V and FF of 0.417. But with front end passivation using Al2O3 (8Å), cell efficiency improved to10.352% with a Jsc of 32.121mA/cm2, Voc of 0.51V and FF of 0.631. With passivation using Al2O3 (8Å) at the front end as well as at the rear end, Voc improved to 0.57V and efficiency was 14.353%. Jsc and FF obtained for this cell were 35.624mA/cm2 and 0.707, respectively. With passivation using Al2O3 (8Å) at the front end and using Al2O3+HfO2 (8Å) at the rear end, Voc improved to 0.58V and efficiency to 14.957% with a Jsc of 36.31 mA/cm2 and FF of 0.71. Finally with passivation using HfO2 (8Å) at the front end as well as at the rear end, efficiency of the cell increased to 15.542% while Voc improved to 0.59V.

致謝 i
摘要 ii
Abstract iv
Table of Contents v
List of Figures vii
List of Tables x
Chapter 1 Introduction 1
1.1. Background 1
1.2. Motivation 3
1.3. Objectives of this thesis 5
Chapter 2 Theory of Solar Cells and ALD Mechanism 6
2.1. The nature of sunlight 6
2.2. The solar cell 8
2.3. The I-V curve characteristics of solar cells 9
2.3.1. Dark and short circuit currents 10
2.3.2. Open circuit voltage 11
2.3.3. Fill factor 11
2.3.4. Efficiency 12
2.3.5. Series resistance and shunt resistance 12
2.4. Recombination in solar cell 13
2.4.1. Recombination through defect levels 14
2.4.2. Lifetime 15
2.4.3. Diffusion length 16
2.4.4. Surface recombination 17
2.5. ALD (Atomic Layer Deposition) 19
2.5.1. Principle of ALD 19
2.5.2. Precursor chemistry of ALD 22
Chapter 3 Experimental Methods 24
3.1. Experimental process flow for CV sample 24
3.1.1. Fabrication of high-κ thin film 25
3.1.2. Oxygen-gas-annealing 27
3.1.3. Deposition of the front electrode 28
3.1.4. Deposition of the back electrode 30
3.1.5. Analysis and measurement 31
3.2. Experimental process flow for the fabrication of solar cell cells 38
3.2.1 Si samples with pyramid textures 39
3.2.2 RCA clean 39
3.2.3 Doping of the Si samples by diffusion 40
3.2.4 Deposition of high-κ film (8-Å) 40
3.2.5 High-κ film anneal 41
3.2.6 Deposition of the front metal electrode 41
3.2.7 Deposition of the rear metal electrode 42
3.2.8 Deposition of ARC 42
Chapter 4 Results and Discussion 43
4.1. The results of CV and lifetime measurement 43
4.1.2. Lifetime measurement of Al2O3-HfO2 films 49
4.1.3. The oxygen-gas-annealing 50
4.2. Characteristics of the solar cells 54
Chapter 5 Conclusion and Future Works 62
5.1. Conclusion 62
5.2. Future works 63
References 64

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