Sharma Sachin, Myers-Ward Rachael L, Gaskill Kurt D, Chatzakis Ioannis
Texas Tech University Department of Physics & Astronomy Lubbock Texas TX 79409 USA
U.S. Naval Research Laboratory Washington DC20375 USA.
Nanoscale Adv. 2023 Jan 3;5(2):485-492. doi: 10.1039/d2na00678b. eCollection 2023 Jan 18.
Femtosecond-THz optical pump probe spectroscopy is employed to investigate the cooling dynamics of hot carriers in quasi-free standing bilayer epitaxial graphene with hydrogen interacalation. We observe longer decay time constants, in the range of 2.6 to 6.4 ps, compared to previous studies on monolayer graphene, which increase nonlinearly with excitation intensity. The increased relaxation times are due to the decoupling of the graphene layer from the SiC substrate after hydrogen intercalation which increases the distance between graphene and substrate. Furthermore, our measurements show that the supercollision mechanism is not related to the cooling process of the hot carriers, which is ultimately achieved by electron optical phonon scattering.
飞秒太赫兹光泵浦探测光谱法被用于研究具有氢插入的准独立双层外延石墨烯中热载流子的冷却动力学。与之前对单层石墨烯的研究相比，我们观察到更长的衰减时间常数，范围在2.6到6.4皮秒之间，且其随激发强度非线性增加。弛豫时间增加是由于氢插入后石墨烯层与碳化硅衬底解耦，这增加了石墨烯与衬底之间的距离。此外，我们的测量表明，超碰撞机制与热载流子的冷却过程无关，热载流子的冷却最终是通过电子与光学声子散射实现的。
