Fakultät für Physik and CeNIDE, Universität Duisburg-Essen, Duisburg, Germany.
Nanotechnology. 2011 Jul 1;22(26):265703. doi: 10.1088/0957-4484/22/26/265703. Epub 2011 May 17.
We present atomic force microscopy and scanning Kelvin probe data obtained under ultra-high vacuum conditions from graphene exfoliated on crystalline SrTiO(3) substrates. The contact potential difference shows a monotonic increase with the number of graphene layers until after five layers of saturation is reached. By identifying the saturation value with the work function of graphite we determine the work function of single and bilayer graphene to be Φ(SLG) = 4.409 ± 0.039 eV and Φ(BLG) = 4.516 ± 0.035 eV, respectively. In agreement with the higher work function of single-layer graphene with respect to free-standing graphene, our measurements indicate an accumulation of charge carriers corresponding to a doping of the exfoliated graphene layer with electrons.
我们呈现了在超高真空条件下从 SrTiO(3) 晶体衬底上剥离的石墨烯获得的原子力显微镜和扫描 Kelvin 探针数据。接触电势差随着石墨烯层数的增加呈单调增加，直到达到五层饱和。通过将饱和值与石墨的功函数进行匹配，我们确定了单层和双层石墨烯的功函数分别为 Φ(SLG) = 4.409 ± 0.039 eV 和 Φ(BLG) = 4.516 ± 0.035 eV。与单层石墨烯相对于自由-standing 石墨烯具有更高的功函数一致，我们的测量表明存在载流子的积累，对应于剥离石墨烯层的电子掺杂。
