a-Si:H薄膜中SiyHx结构组态的原子模拟研究

翟世铭; 廖黄盛; 周耐根; 黄海宾; 周浪

doi:10.7498/aps.69.20191275

摘要

氢化非晶硅薄膜(a-Si:H)中Si_yH_x结构组态对薄膜应用性能有重要影响, 然而现有的分析测试手段难以对其进行深入细致的研究. 本文运用分子动力学方法模拟分析了a-Si:H/c-Si薄膜中Si_yH_x结构组态, 以及衬底温度对其含量的影响; 并进一步运用第一性原理方法计算了各Si_yH_x组态中的Si-H键能. 结果发现a-Si:H薄膜中Si_yH_x结构可以归纳为六种组态. 三类为以化学键结合的SiH_x组态, 包括SiH, SiH₂和SiH₃; 另外三类为以物理键结合的HSi_y组态, 包括HSi₂(s), HSi₂(l)和HSi₃. 键能结果反映出六种组态的稳定性由高到低的顺序为SiH > SiH₂ > SiH₃ > HSi₂(s) > HSi₂(l) > HSi₃. HSi_y组态中Si—H键能在太阳光中的可见光和红外线的能量范围内, 阳光照射引起HSi_y组态中的Si-H物理键断裂, 是非晶硅薄膜电池产生S-W (Steabler-Wronski)效应的主要机理. 另外, 薄膜沉积过程中衬底温度的升高将导致各类Si_yH_x组态含量大幅降低.

关键词:

Abstract

The hydrogenated amorphous silicon (a-Si:H) film is the core structure of hetero junction with intrinsic thin layer solar cell. Its quality determinates the photoelectric conversion efficiency of this solar cell directly. The configuration of Si_yH_x is an important structure characteristic of a-Si:H films, and it can influence on the quality of a-Si:H thin films and their application properties. However, it is difficult to study them in depth and detail by the existing analytical and testing methods. In this paper, the structure configuration of Si_yH_x in a-Si:H /c-Si thin films and the effect of substrate temperature on its content have been simulated and analyzed by molecular dynamics method. A modified Tersoff potential developed by Murty was used to calculate the inter-atomic forces. The results showed that the Si_yH_x structure in a-Si:H thin films can be summarized into six configurations. Three traditional configurations, including SiH, SiH₂ and SiH₃, can be referred to as SiH_x configurations.The other three nove configurations, including HSi₂(s), HSi₂(l) and HSi₃, can be referred to as HSi_y configurations. The main differences between the configurations of HSi₂(l) and HSi₂(s) are the longer Si—H bonds and bigger bond angle in HSi₂(l) configuration than those in HSi₂(s) configuration. All of the Si-H bonds in SiH_x configurations are strong chemical bonds, while the Si—H bonds in HSi_yconfigurations are weak physical bonds. The further calculations of the Si-H bond energies in six configurations have been carried out by the first principle method. According the bond energies results, we can deduce that the order of the stability of six configurations from high to low is SiH > SiH₂ > SiH₃ > HSi₂(s) > HSi₂(l) > HSi₃. Comparing the Si—H bond energies of the six configurations with the solar energy, it is found that the Si-H bond energy in HSi_y configuration is in the range of visible and infrared light in solar light. Si—H physical bonds are easy to fracture in HSi_y configuration caused by solar light. This may be the main mechanism of producing Steabler-Wronski (S-W) effect in amorphous silicon thin film cells. In addition, the rise of substrate temperature in the deposition process of a-Si:H films will lead to a significant decrease in the configuration content of all kinds of Si_yH_xconfigurations.

Keywords:

Si_yH_x configuration /
bond energy /
hydrogenated amorphous silicon thin films (a-Si:H) /
molecular dynamics

作者及机构信息

南昌大学材料科学与工程学院, 光伏研究院, 南昌　330031

通信作者: 周耐根, ngzhou@ncu.edu.cn ; 黄海宾, haibinhuang@ncu.edu.cn ;

基金项目: 国家级-氢化非晶硅薄膜局域结构特征及其形成的分子动力学模拟研究(51561022)

Authors and contacts

School of Materials Science and Engineering, Institute of Photovoltaics, Nanchang University, Nanchang 330031, China

Corresponding author: Zhou Nai-Gen, ngzhou@ncu.edu.cn ; Huang Hai-Bin, haibinhuang@ncu.edu.cn ;

文章全文

参考文献

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施引文献

图 1 晶体硅衬底表面沉积生长a-Si:H/c-Si薄膜的模型结构示意图

Fig. 1. Schematic diagram of the model structure about a-Si:H thin film deposited on the surface of crystalline silicon substrate.

下载: 全尺寸图片幻灯片

图 2 衬底温度为500 K时, 入射约8000个基团得到的a-Si:H/c-Si薄膜的原子结构示意图(a) 和薄膜层的RDF图(b)

Fig. 2. Atomic structure of a-Si:H/c-Si film after depositing about 8000 groups with the substrate temperature of 500 K (a) and RDF curve of the film layer (b).

下载: 全尺寸图片幻灯片

图 3 a-Si:H薄膜中Si-H键的键长分布　(沉积条件: 衬底温度为500 K, 入射动能为1.45 eV, 入射频率为1 ps/个基团)

Fig. 3. The bond length distribution of the Si-H bond in the a-Si:H film (Deposition conditions: substrate temperature is 500 K, the incident kinetic energy is 1.45 eV, and the incident frequency is 1 ps/group).

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图 4 a-Si:H薄膜中Si_yH_x组态的结构示意图　(a) SiH; (b) SiH₂; (c) SiH₃; (d) HSi₂(s); (e) HSi₂(l); (f) HSi₃

Fig. 4. The structure Schematic diagram of Si_yH_x in the a-Si:H film: (a) SiH; (b) SiH₂; (c) SiH₃; (d) HSi₂(s); (e) HSi₂(l); (f) HSi₃.

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图 5 各Si_yH_x组态中Si-H键能与太阳光能量对比图

Fig. 5. Comparisons of Si-H bond energy in each Si_yH_x configuration with solar energy

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图 6 不同衬底温度下沉积生长的a-Si:H/c-Si薄膜中的悬挂键、SiH_x和HSi_y相对含量(a), SiH, SiH₂和SiH₃的相对含量(b)和HSi₂(s), HSi₂(l)和HSi₃相对含量(c)

Fig. 6. Relative contents of dangling bonds, SiH_x and HSi_y(a), relative contents of SiH, SiH₂ and SiH₃ (b), and relative content of HSi₂(s), HSi₂ (l) and HSi₃ (c) in a-Si:H/c-Si films deposited with different substrate temperatures.

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[1]	Yoshikawa K, Kawasaki H, Yoshida W, Irie T, Konishi K, Nakano K, Uto T, Adachi D, Kanematsu M, Uzu H, Yamamoto K 2017 Nat. Energy 2 17032 Google Scholar
[2]	Liu J, Huang S H, He L 2015 J. Semicond. 36 4 Google Scholar
[3]	Mishima T, Taguchi M, Sakata H, Maruyama E 2011 Sol. Energy Mater. Sol. Cells 95 18 Google Scholar
[4]	Li Z, Zhang X W, Han G R 2010 Phys. Status Solidi A 207 144 Google Scholar
[5]	Masuko K, Shigematsu M, Hashiguchi T, Fujishima D, Kai M, Yoshimura N, Yamaguchi T, Ichihashi Y, Mishima T, Matsubara N, Yamanishi T, Takahama T, Taguchi M, Maruyama E, Okamoto S 2014 IEEE. J. Photovoltaics 4 1433 Google Scholar
[6]	Luo Y R, Gong H Y, Zhou N G, Huang H B, Zhou L 2018 Appl. Phys. A 124 18 Google Scholar
[7]	Illiberi A, Creatore M, Kessels W M M, de Sanden M 2010 Phys. Status SolidiR 4 206 Google Scholar
[8]	Bronsveld P C P, Mates T, Fejfar A, Kocka J, Rath J K, Schropp R E I 2010 Phys. Status Solidi A 207 525 Google Scholar
[9]	Luo Y, Zhou N, Gong H, Huang H, Lang Z 2018 IOP Conf. Ser.: Mater. Sci. Eng. 284 012006 Google Scholar
[10]	Hou G F, Fan Q H, Liao X B, Chen C Y, Xiang X B, Deng X M 2011 J. Vac. Sci. Technol., A 29 061201 Google Scholar
[11]	Andujar J L, Bertran E, Canillas A, Roch C, Morenza J L 1991 J. Vac. Sci. Technol., A 9 2216 Google Scholar
[12]	Staebler D L, Wronski C R 1977 Appl. Phys. Lett. 31 292 Google Scholar
[13]	Zhang D, Tavakoliyaraki A, Wu Y, van Swaaij R, Zeman M 2011 Energy Procedia 8 207 Google Scholar
[14]	Alnuaimi A, Islam K, Nayfeh A 2013 Sol. Energy 98 236 Google Scholar
[15]	秦国刚, 孔光临 1988 半导体学报 01 103 Google Scholar Qin G G, Kong G L 1988 J. Semicond. 01 103 Google Scholar
[16]	Murty M V R, Atwater H A 1995 Phys. Rev. B 51 4889 Google Scholar
[17]	Tersoff J 1988 Phys. Rev. B 37 6991 Google Scholar
[18]	Macrae C F, Bruno I J, Chisholm J A, Edgington P R, Wood P A 2008 J. Appl. Crystallogr. 41 466 Google Scholar
[19]	Hafner J, Kresse G 1997 Properties of Complex Inorganic Solids (New York: Plenum Press) pp69–99
[20]	Sriraman S, Agarwal S, Aydil E S, Maroudas D 2002 Nature 418 62 Google Scholar
[21]	Robertson J 2000 J. Non-Cryst. Solids 266 79 Google Scholar
[22]	Kim H, Horwitz J S, Kushto G, Piqué A, Kafafi Z H, Gilmore C M, Chrisey D B 2000 J. Appl. Phys. 88 6021 Google Scholar

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a-Si:H薄膜中Si_yH_x结构组态的原子模拟研究