【作者】 林立； 彭海琳； 刘忠范；

【Author】 Li Lin;Hailin Peng;Zhongfan Liu;Center for Nanochemistry, College of Chemistry and Molecular Engineering, Peking University;

【机构】 北京大学化学与分子工程学院；

【摘要】 石墨烯是一种由sp~2杂化碳原子组成的二维原子晶体,其优异的电学和光学等特性,使得它在光电器件有广泛的应用前景。石墨烯光电器件因为石墨烯载流子寿命低,需要构筑石墨烯PN结来实现光生载流子的有效分离~[1]。石墨烯PN结的功函差值一定程度上决定了石墨烯光电转换效率,但目前的石墨烯PN功函差值在几百电子伏特。石墨烯掺杂可以实现对石墨烯费米能级位置的有效调节,利用硼或氮元素对石墨烯进行骨架掺杂是其中一种有效的调节石墨烯功函的手段~[2]。我们提出了一种通过高温裂解富含不同掺杂元素的反应物,调制掺杂规模制备高质量的硼氮分区掺杂石墨烯的方法,成功地构筑石墨烯面内PN结。俄歇电子能谱(AES)分析证实硼元素和氮元素实现分区掺杂。角分辨光电子能谱(ARPES)证实,通过控制不同掺杂反应温度,硼掺杂石墨烯和氮掺杂石墨烯的功函差值可以达到1 eV。进而光电测试证实,此类石墨烯面内PN结具有较高的光电转换效率。更多还原

【Abstract】 Graphene is the two-dimensional atomic crystal made of sp~2-hybridized carbon atoms with extraordinary electronic and optical properties.~[1] For the graphene p-n junctions used in a photodetector, the need to separate the photogenerated electron-hole pairs is critical, in order to inhibit their fast recombination as their lifetime is typically quite short. It is well known that the efficiency of graphene-based photodetectors can be improved by optimizing the chemical potential difference of the graphene p-n junction. However, up to date, such tuning has been limited to a few hundred milli-electron volts. Doping graphene with substitutional heteroatoms like boron and nitrogen provides an effective approach to tune the Fermi Level(EF) of graphene.~[2] We successfully achieved modulation-doped growth of an alternately nitrogen-and boron-doped graphene p-n junction with a tunable chemical potential difference up to 1 eV, as confirmed by angle-resolved photoemission spectroscopy(ARPES) measurements. The chemical potential difference across the p-n junction can be tuned to realize an enhanced photoelectrical conversion.更多还原