Maity G, Dubey S, El-Azab Anter, Singhal R, Ojha S, Kulriya P K, Dhar S, Som T, Kanjilal D, Patel Shiv P
Department of Pure & Applied Physics, Guru Ghasidas Vishwavidyalaya (A Central University) Bilaspur-495009 India
Department of Physics, School of Engineering, University of Petroleum & Energy Studies Bidholi Dehradun-248007 India.
RSC Adv. 2020 Jan 27;10(8):4414-4426. doi: 10.1039/c9ra08836a. eCollection 2020 Jan 24.
In the present study, crystallization of amorphous-Si (a-Si) in Al/a-Si bilayer thin films under thermal annealing and ion irradiation has been investigated for future solar energy materials applications. In particular, the effect of thickness ratio ( in Al : a-Si, the ratio of the Al and a-Si layer thickness) and temperature during irradiation on crystallization of the Si films has been explored for the first time. Two sets of samples with thickness ratio 1 : 1 (set-A: 50 nm Al/50 nm a-Si) and thickness ratio 1 : 3 (set-B: 50 nm Al/150 nm a-Si) have been prepared on thermally oxidized Si-substrates. In one experiment, thermal annealing of the as-prepared sample (of both the sets) has been done at different temperatures of 100 °C, 200 °C, 300 °C, 400 °C, and 500 °C. Significant crystallization was found to initiate at 200 °C with the help of thermal annealing, which increased further by increasing the temperature. In another experiment, ion irradiation on both sets of samples has been carried out at 100 °C and 200 °C using 100 MeV Ni ions with fluences of 1 × 10 ions per cm, 5 × 10 ions per cm, 1 × 10 ions per cm, and 5 × 10 ions per cm. Significant crystallization of Si was observed at a remarkably low temperature of 100 °C under ion irradiation. The samples irradiated at 100 °C show better crystallization than the samples irradiated at 200 °C. The maximum crystallization of a-Si has been observed at a fluence of 1 × 10 ions per cm, which was found to decrease with increasing ion fluence at both temperatures ( 100 °C & 200 °C). The crystallization of a-Si is found to be better for set-B samples as compared to set-A samples at all the fluences and irradiation temperatures. The present work is aimed at developing the understanding of the crystallization process, which may have significant advantages for designing crystalline layers at lower temperature using appropriate masks for irradiation at the desired location. The detailed mechanisms behind all the above observations are discussed in this paper.
在本研究中，针对未来太阳能材料应用，对Al/a-Si双层薄膜在热退火和离子辐照下非晶硅（a-Si）的结晶情况进行了研究。特别地，首次探讨了厚度比（Al与a-Si的厚度比）以及辐照过程中的温度对Si薄膜结晶的影响。在热氧化的Si衬底上制备了两组厚度比分别为1:1（A组：50 nm Al/50 nm a-Si）和1:3（B组：50 nm Al/150 nm a-Si）的样品。在一个实验中，对制备好的样品（两组）在100℃、200℃、300℃、400℃和500℃的不同温度下进行热退火。发现借助热退火在200℃时开始显著结晶，并且随着温度升高结晶进一步增加。在另一个实验中，使用能量为100 MeV、通量分别为每平方厘米1×10离子、5×10离子、1×10离子和5×10离子的Ni离子，在100℃和200℃对两组样品进行离子辐照。在离子辐照下，在100℃这一相当低的温度下观察到Si有显著结晶。在100℃辐照的样品比在200℃辐照的样品结晶更好。在每平方厘米1×10离子的通量下观察到a-Si的最大结晶，发现在两个温度（100℃和200℃）下随着离子通量增加结晶减少。发现在所有通量和辐照温度下，B组样品的a-Si结晶比A组样品更好。本工作旨在增进对结晶过程的理解，这对于在较低温度下使用合适的掩膜在期望位置进行辐照来设计结晶层可能具有显著优势。本文讨论了上述所有观察结果背后的详细机制。
