Infrared study of large scale h-BN film and graphene/h-BN heterostructure
Infrared study of large scale h-BN film and graphene/h-BN heterostructure
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DOI：
10.1063/1.4954171
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发表时间：
2016-06
影响因子：
4
通讯作者：
Kwangnam Yu;Jiho Kim;C. Lee;A. Jang;H. Shin;K. Kim;Young‐Jun Yu;E. Choi
中科院分区：
文献类型：
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作者：
Kwangnam Yu;Jiho Kim;C. Lee;A. Jang;H. Shin;K. Kim;Young‐Jun Yu;E. Choi
我们合成了一系列的CVD h-BN薄膜，并进行了临界红外光谱表征。对于高温(高温，温度=1400°C)生长的h-BN薄膜，由于h-BN平面的倾斜堆积，只有E1u模红外声子被激活，显示出大面积高度取向的2D h-BN面，而低温(LT，温度=1000°C)生长的薄膜由于h-BN面的倾角堆积，出现了两个声子峰：E1u和A2u。对于在HTh-BN/SiO_2/Si衬底上转移的化学气相沉积石墨烯，能带间跃迁光谱σ_1比在LT_h-BN/SiO_2/Si衬底和裸SiO_2/Si衬底上的谱带跃迁能量显著降低，表明高温H-BN层的存在抑制了石墨烯中的剩余载流子密度n。由有效温度定义的σ-1带间跃迁宽度从G/SiO_2/Si的400K减小到HTh-BN/SiO_2/Si的300K。N和有效温度的行为表明，HTh-BN薄膜可以将CVD石墨烯与二氧化硅的杂质和缺陷解耦，从而获得了大规模的自支撑石墨烯。
We synthesize a series of CVD h-BN films and perform critical infrared spectroscopic characterization. For high-temperature (HT, Temp = 1400 °C) grown h-BN thin film, only E1u-mode infrared phonon is activated demonstrating highly aligned 2D h-BN planes over large area, whereas low-temperature (LT, Temp = 1000 °C) grown film shows two phonon peaks, E1u and A2u, due to stacking of h-BN plane at tilted angle. For CVD graphene transferred on HT h-BN/SiO2/Si substrate, interband transition spectrum σ1 shifts strongly to lower energy compared with that on LT h-BN/SiO2/Si and on bare SiO2/Si substrates, revealing that the residual carrier density n in graphene is suppressed by the use of HT h-BN layer. Also, the interband transition width of σ1 defined by effective temperature is reduced from 400 K for G/SiO2/Si to 300 K for HT h-BN/SiO2/Si. The behaviors of n and effective temperature show that the HT h-BN film can decouple CVD graphene from the impurity and defect of SiO2 leading to a large scale free-standin...