p型微晶硅膜的研究及其在異質(zhì)結(jié)太陽(yáng)電池中的應(yīng)用
首先采用射頻等離子體增強(qiáng)化學(xué)氣相沉積技術(shù)制備了電導(dǎo)率為0.13 S/cm、晶化率為50%的p型微晶硅,然后制備了μc-Si∶H(p)/c-Si(n)異質(zhì)結(jié)太陽(yáng)電池。初步研究了硼摻雜比、輝光功率密度、p型硅薄膜的厚度和氫處理時(shí)間等這些參數(shù)對(duì)電池開(kāi)壓的影響。在優(yōu)化的工藝參數(shù)下得到異質(zhì)結(jié)電池最大開(kāi)路電壓Voc為564mV。
p型薄膜硅;異質(zhì)結(jié)太陽(yáng)電池;開(kāi)路電壓;射頻等離子體增強(qiáng)化學(xué)氣相沉積
Abstract: The p-type microcrystalline(μc) silicon thin films were grown by RF plasma enhanced chemical vapor deposition(RF-PECVD) on glass substrates,and the μc-Si:H(p)/c-Si(n) hetero-junction solar cells were fabricated with the films.The impacts of the growth conditions,such as the pressure,boron-doping,discharge power,substrate temperature,gas flow rate,and concentration of silane,on the microstructures and properties of the films were studied.The current-voltage characteristics of the hetero-junction were evaluated.The preliminary results show that the solar cells,made of the films grown under optimized film growth conditions,works well with an open-circuit voltage of 564 mV.Possible improvement of the μc-Si film growth was also tentatively discussed.
Keywords: Microcrystalline silicon films,Heterojunction solar cells,Open-circuit voltage,RF-PECVD
基金項(xiàng)目: 國(guó)家重點(diǎn)研究發(fā)展規(guī)劃(批準(zhǔn)號(hào):2006CB202601);; 河南省基礎(chǔ)與前沿技術(shù)研究計(jì)劃(批準(zhǔn)號(hào):82300443203)資助的課題
氫化微晶硅( c-SiH) 薄膜是由納米晶硅、晶粒邊界、非晶硅和空洞等構(gòu)成的混合相材料, 它具有高摻雜效率、高電導(dǎo)率以及大的載流子遷移率等優(yōu)點(diǎn),同時(shí)還具有比氫化非晶硅更寬的光譜響應(yīng)范圍[1],因此在薄膜太陽(yáng)電池中有著廣泛的應(yīng)用; 許多研究已經(jīng)證明硼摻雜p 型微晶硅非常適合做微晶PIN 電池的窗口材料[ 2- 3] 。目前制備p 型氫化微晶硅的常用沉積技術(shù)有: 等離子體增強(qiáng)化學(xué)氣相沉積(PECVD) 、熱絲化學(xué)氣相沉積( HWCVD) 和微波化學(xué)氣相沉積, 常用摻雜氣源有B2H6, B( CH3 ) 3 和BF3,其中PECVD 常用的是B2H6。
在c-Si 上生長(zhǎng)一層氫化非晶硅或氫化微晶硅薄膜形成的異質(zhì)結(jié)太陽(yáng)電池, 這種電池p-n 結(jié)制備采用了薄膜沉積的低溫工藝( < 200 ) , 不僅減少了能耗, 又避免了硅片在高溫過(guò)程中性能的退化, 同時(shí)又發(fā)揮了晶體硅材料的高性能的優(yōu)勢(shì), 因此, 硅異質(zhì)結(jié)太陽(yáng)電池兼具高效率、穩(wěn)定和低成本的優(yōu)點(diǎn), 展示出更為廣闊的應(yīng)用前景。目前國(guó)外對(duì)這種電池的研究發(fā)展非常迅速, Mikio Taguchi 等[ 4] 成功地在1004m2 的硅片上獲得了效率高達(dá)23% ( 經(jīng)AIST 測(cè)定)的HIT 太陽(yáng)電池, 但是國(guó)內(nèi)有關(guān)異結(jié)電池的研究水平還很落后, 到目前為止, 最高的轉(zhuǎn)換效率為17.27%[ 5] , 因此很有必要對(duì)這種異質(zhì)結(jié)電池開(kāi)展進(jìn)一步的研究。
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