Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-747, Republic of Korea.
ACS Nano. 2013 Jul 23;7(7):5850-7. doi: 10.1021/nn402354j. Epub 2013 Jun 21.
With its electrical carrier type as well as carrier densities highly sensitive to light, graphene is potentially an ideal candidate for many optoelectronic applications. Beyond the direct light-graphene interactions, indirect effects arising from induced charge traps underneath the photoactive graphene arising from light-substrate interactions must be better understood and harnessed. Here, we study the local doping effect in graphene using focused-laser irradiation, which governs the trapping and ejecting behavior of the charge trap sites in the gate oxide. The local doping effect in graphene is manifested by large Dirac voltage shifts and/or double Dirac peaks from the electrical measurements and a strong photocurrent response due to the formation of a p-n-p junction in gate-dependent scanning photocurrent microscopy. The technique of focused-laser irradiation on a graphene device suggests a new method to control the charge-carrier type and carrier concentration in graphene in a nonintrusive manner as well as elucidate strong light-substrate interactions in the ultimate performance of graphene devices.
由于其载流子类型以及载流子密度对光高度敏感，石墨烯是许多光电应用的理想候选材料。除了直接的光-石墨烯相互作用之外，还必须更好地理解和利用由光-衬底相互作用引起的光活性石墨烯下方感应电荷陷阱的间接效应。在这里，我们使用聚焦激光照射研究了石墨烯中的局部掺杂效应，该效应控制了栅极氧化物中电荷陷阱位的捕获和释放行为。通过电测量得到的大狄拉克电压位移和/或双狄拉克峰以及栅极扫描光电电流显微镜中由于形成 p-n-p 结而产生的强光电流响应，表现出石墨烯中的局部掺杂效应。聚焦激光照射在石墨烯器件上的技术提出了一种新的方法，可在不干扰的情况下以非侵入性方式控制石墨烯中的电荷载流子类型和载流子浓度，并阐明石墨烯器件最终性能中的强光-衬底相互作用。
