Rahman Md Habibur, Mitra Shailee, Motalab Mohammad, Bose Pritom
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology Dhaka-1000 Bangladesh
RSC Adv. 2020 Aug 25;10(52):31318-31332. doi: 10.1039/d0ra06085b. eCollection 2020 Aug 21.
Silicon doping is an effective way to modulate the bandgap of graphene that might open the door for graphene to the semiconductor industries. However, the mechanical properties of silicon doped graphene (SiG) also plays an important role to realize its full potential application in the electronics industry. Electronic and optical properties of silicon doped graphene are well studied, but, our understanding of mechanical and fracture properties of the doped structure is still in its infancy. In this study, molecular dynamics (MD) simulations are conducted to investigate the tensile properties of SiG by varying the concentration of silicon. It is found that as the concentration of silicon increases, both fracture stress and strain of graphene reduces substantially. Our MD results also suggest that only 5% of silicon doping can reduce the Young's modulus of graphene by ∼15.5% along the armchair direction and ∼13.5% along the zigzag direction. Tensile properties of silicon doped graphene have been compared with boron and nitrogen doped graphene. The effect of temperature, defects and crack length on the stress-strain behavior of SiG has also been investigated. Temperature studies reveal that SiG is less sensitive to temperature compared to free stranding graphene, additionally, increasing temperature causes deterioration of both fracture stress and strain of SiG. Both defects and cracks reduce the fracture stress and fracture strain of SiG remarkably, but the sensitivity to defects and cracks for SiG is larger compared to graphene. Fracture toughness of pre-cracked SiG has been investigated and results from MD simulations are compared with Griffith's theory. It has been found that for nano-cracks, SiG with larger crack length deviates more from Griffith's criterion and the degree of deviation is larger compared to graphene. Fracture phenomenon of pre-cracked SiG and the effect of strain rate on the tensile properties of SiG have been reported as well. These results will aid the design of SiG based semiconducting nanodevices.
硅掺杂是调节石墨烯带隙的有效方法，这可能为石墨烯进入半导体行业打开大门。然而，硅掺杂石墨烯（SiG）的机械性能对于其在电子行业实现全面潜在应用也起着重要作用。硅掺杂石墨烯的电学和光学性质已得到充分研究，但我们对掺杂结构的机械和断裂性能的理解仍处于起步阶段。在本研究中，通过改变硅的浓度，进行分子动力学（MD）模拟来研究SiG的拉伸性能。研究发现，随着硅浓度的增加，石墨烯的断裂应力和应变均大幅降低。我们的MD结果还表明，仅5%的硅掺杂就能使石墨烯的杨氏模量沿扶手椅方向降低约15.5%，沿锯齿方向降低约13.5%。已将硅掺杂石墨烯的拉伸性能与硼和氮掺杂石墨烯进行了比较。还研究了温度、缺陷和裂纹长度对SiG应力 - 应变行为的影响。温度研究表明，与游离的石墨烯相比，SiG对温度不太敏感，此外，温度升高会导致SiG的断裂应力和应变均恶化。缺陷和裂纹都会显著降低SiG的断裂应力和断裂应变，但SiG对缺陷和裂纹的敏感性比石墨烯更大。已研究了预裂纹SiG的断裂韧性，并将MD模拟结果与格里菲斯理论进行了比较。研究发现，对于纳米裂纹，具有较大裂纹长度的SiG与格里菲斯准则的偏差更大，且与石墨烯相比，偏差程度更大。还报道了预裂纹SiG的断裂现象以及应变率对SiG拉伸性能的影响。这些结果将有助于基于SiG的半导体纳米器件的设计。
