NON-Conventional Grating Solar Cell

非典型欄柵型太陽能電池

陳國盛(Guo-Sheng Chen)

指導教授 ： 黃惠良 ； 裴靜偉

國立清華大學/電機資訊學院/電子工程研究所/碩士(2008年)

摘要

This thesis represents the characteristics of low temperature (uc-Si) films deposition on grating , silicon substrates and the solar cell that was fabricated by this films. We deposit the u-Si films by high density plasma chemical vapor deposition (HDP-CVD).
The Characterization of films were carried out by using Raman scattering, XRD, SEM, SRP, α-STEP, and Four point probe. Raman scattering spectra was being used to investigating their crystallinity and the crystalline fraction in the u-Si films as well as the X-ray diffraction pattern (XRD) spectra was being used to analyzing the preferred orientation of the u-Si films. The fourier transform infrared (FTIR) absorption spectra was being used to studying the silicon-hydrogen bonding configurations along with the hydrogen content of the Si films. Conductive measurements were being engaged to studying the electrical properties of a-Si films; Furthermore the Nanospac and α-STEP were being managed to measuring films thickness; Scanning electron microscopy (SEM) was being used to analyzing grain geometry along with the top morphology while Spreading Resistance Profiling (SRP) and Four point probe were being used to analyzing the doping concentration and resistivity.
While preparing the i, and n layers of solar cells by using HDPCVD, the growing conditions were found in our experiments. The experimental parameters was being used in substrate temperature at 160 oC (for both, doped and undoped films), the microwave power at 890W, the range of the process pressure at 6mtorr. The hydrogen dilution ratio was varied in order to analyze the characteristics of thin films. In addition, we also doped the films by using Arsine (AsH3) and by forming the n-type silicon thin film.
The results of these experiments show that the preferred orientation of the uc-Si films were found to be <111>, and also it was observed that the hydrogen content decreased along with the increase of hydrogen dilution ratio. The doping concentration of N-type is somewhat 7e15cm-3.
We use the electrical-chemical etching to develop the grating structure, along with the thin film. We are anticipating that the electric current might have large scale of improvement thanks to the grating structure has large cross-sectional area. we will end up getting larger electric current within our expectations.
We use DMSO and HF as the etching solution. We found that with the more concentrated and thicker solution that condenses the holes in between as well as higher electric current, the higher speed of the etching rate will be produced. On the other hand, the results apply.
At last, we have used thin film with concentrated etching solution 3M, the depth approximately 5um, diameter 1.5um of the hole, electric current 5 mA with resistivity 2 omic-cm and 30 minutes process of using electrical-chemical etching to be performed as our substrates. The result shows that it is better to have the grating structure solar cell with short circuit, open circuit voltage more than the plane one. It produces higher efficient consequence. The best one was 1.62% among our records.

關鍵字

太陽電池 ； 高密度電漿 ； 欄柵

並列摘要

本論文主旨在討論低溫微晶矽薄膜於柵欄型結構成長之太陽能電池，利用高密度電漿化學氣相沉積(HDP-CVD)系統以氫稀釋法來成長矽薄膜，並利用拉曼(Raman)散射頻譜則用於分析微晶矽薄膜之結晶度與結晶態體積含量，X-ray 繞射頻譜則用於分析微晶矽薄膜之擇優取向 (Preferred orientations)，紅外線吸收頻譜可分析微晶矽薄膜的氫-矽之鍵結組態及薄膜中的氫含量、導電度分析用來解析微晶矽薄膜之導電特性，而Nanospac及α-STEP測厚儀用來量測薄膜厚度，掃描式電子顯微鏡(SEM)做表面晶粒型態分析，展阻量測儀(SRP)及四點探針用來量測參雜濃度等特性進行分析。
在實驗過程中我們控制基板溫度在(160℃)範圍、微波功率為890瓦特，壓力為5X10-5托 ，改變氫稀釋比例進行薄膜分析。此外，我們也在矽薄膜中摻雜AsH3氣體形成N型矽薄膜並利用SRP對其電阻率進行量測分析。
實驗結果顯示，非摻雜型微晶矽薄膜的擇優取向為<111>，氫含量也隨著氫稀釋比增加而減少。在摻雜方面，N-type濃度在7.0e15cm-3。
我們使用電化學蝕刻做出Grating結構，之後再與薄膜作結合，跟以往不同的平面基板，再比較效率，電流的關係，我們可以預期的，因為柵欄型結構有一個更大的截面積，因此電流會增加。
我們使用DMSO和HF作為蝕刻溶液，當溶液濃度越高，孔跟孔之間距越密，蝕刻速率越高，反之亦然。當電流越高，蝕刻速率越高，但孔洞會越密。
在這個實驗，我們使用了濃度3M，電流5 mA， 30分鐘定電流蝕刻。孔洞深度大約5um，孔徑1.5um，阻值2歐姆-cm作為薄膜沉積的基板。結果顯示有柵欄型結構的基板比平面積板所做成的太陽能電池其短路電流，開路電壓，效率都有明顯的提高最好的效率為1.62%。

並列關鍵字

Solar cell ； HDP-CVD ； Grating

參考文獻

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