Transparent conductive Mg and Ga co-doped ZnO thin films for solar cells grown by magnetron sputtering: H2 induced changes
Transparent conductive Mg and Ga co-doped ZnO thin films for solar cells grown by magnetron sputtering: H2 induced changes
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DOI：
10.1016/j.solmat.2014.02.028
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发表时间：
2014-06
影响因子：
6.9
通讯作者：
Cong-sheng Tian;Xinliang Chen;J. Ni;Jie-ming Liu;Dekun Zhang;Qian Huang;Ying Zhao;Xiaodang Zhang
中科院分区：
文献类型：
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作者：
Cong-sheng Tian;Xinliang Chen;J. Ni;Jie-ming Liu;Dekun Zhang;Qian Huang;Ying Zhao;Xiaodang Zhang
采用脉冲直流磁控溅射法，在553 K的衬底温度下，在玻璃衬底上制备了用于太阳能电池的氢化Mg和Ga共掺杂ZnO（HMGZO）透明导电薄膜。HMGZO薄膜的结构，形态，电气和光学性能进行了研究与不同的H2流量。实验结果表明，HMGZO薄膜为六方纤锌矿结构，具有（002）晶面择优取向，典型的HMGZO薄膜表面为锥状织构。随着H2流量从0 sccm增加到4.0 sccm，载流子浓度从7.57× 1019 cm-3迅速增加到5.25× 1020 cm-3。光学测量表明，HMGZO薄膜的光学带隙（Eg）随H2流量从0 sccm到4.0 sccm的变化范围为3.43 eV到3.66 eV。在4.0 sccm的H2流速下沉积的玻璃/HMGZO薄膜在340 nm至1100 nm的波长范围内表现出最低的电阻率6.24×10−4Ω cm（薄层电阻Rs ~8.68 Ω）和78.8%的平均透射率（Ta）。Burstein-Moss带填充、载流子浓度决定的带隙重正化效应以及Mg原子的掺入共同导致了Eg展宽现象。通过热退火工艺可以有效地提高HMGZO薄膜的电子迁移率。最后将HMGZO薄膜初步应用于pin a-Si：H薄膜太阳电池，其效率为8.20%（Voc=0.904 V，Jsc=12.906 mA/cm 2，FF =0.702）。
Transparent conductive hydrogenated Mg and Ga co-doped ZnO (HMGZO) thin films for solar cells were deposited via pulsed direct current (DC) magnetron sputtering on glass substrates at a substrate temperature of 553 K. The structural, morphological, electrical, and optical properties of HMGZO thin films were investigated with various H2flow rates. The experiment results showed that the HMGZO thin films are polycrystalline with a hexagonal wurtzite structure exhibiting a preferred (002) crystal plane orientation and typical HMGZO thin films present cone-like texture surface. The carrier concentration rapidly increases from 7.57×1019cm−3to 5.25×1020cm−3with increasing the H2flow rate from 0 sccm to 4.0 sccm. Optical measurements indicated that the optical band-gap (Eg) of HMGZO thin films varies from 3.43 eV to 3.66 eV with adjusting H2flow rate from 0 sccm to 4.0 sccm. The glass/HMGZO thin film deposited at the H2flow rate of 4.0 sccm exhibits the lowest resistivity of 6.24×10−4Ω cm (sheet resistanceRs~8.68 Ω) and an average transmittance (Ta) of 78.8% in the wavelength range from 340 nm to 1100 nm. Burstein–Moss band-filling, band gap renormalization effects determined by carrier concentrations and the incorporation of Mg atoms together contribute to anEgwidening phenomenon. The electron mobility of HMGZO thin films can be effectively improved through thermal annealing process. Finally, the HMGZO thin film was preliminarily applied in pin a-Si:H thin film solar cell with an efficiency of 8.20% (Voc=0.904 V,Jsc=12.906 mA/cm2andFF=0.702).