Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
Nano Lett. 2012 Oct 10;12(10):5074-81. doi: 10.1021/nl301551a. Epub 2012 Sep 7.
We demonstrate a combination of micro four-point probe (M4PP) and non-contact terahertz time-domain spectroscopy (THz-TDS) measurements for centimeter scale quantitative mapping of the sheet conductance of large area chemical vapor deposited graphene films. Dual configuration M4PP measurements, demonstrated on graphene for the first time, provide valuable statistical insight into the influence of microscale defects on the conductance, while THz-TDS has potential as a fast, non-contact metrology method for mapping of the spatially averaged nanoscopic conductance on wafer-scale graphene with scan times of less than a minute for a 4-in. wafer. The combination of M4PP and THz-TDS conductance measurements, supported by micro Raman spectroscopy and optical imaging, reveals that the film is electrically continuous on the nanoscopic scale with microscopic defects likely originating from the transfer process, dominating the microscale conductance of the investigated graphene film.
我们展示了微四点探针 (M4PP) 和非接触太赫兹时域光谱 (THz-TDS) 测量的结合，用于对大面积化学气相沉积石墨烯薄膜的片上电导率进行厘米级定量映射。首次在石墨烯上进行的双配置 M4PP 测量提供了对微尺度缺陷对电导率影响的有价值的统计见解，而 THz-TDS 具有作为快速、非接触的晶圆级石墨烯上纳米级电导率空间平均映射的计量方法的潜力，扫描时间小于一分钟对于 4 英寸晶圆。M4PP 和 THz-TDS 电导率测量的结合，辅以微拉曼光谱和光学成像，表明该薄膜在纳米尺度上具有电连续性，而微观缺陷可能源自转移过程，主导了所研究的石墨烯薄膜的微尺度电导率。
