Analysis of <i>p</i>-Type Doping in Graphene Induced by Monolayer-Oxidized TMDs
Tuyen Huynh, Tien Dat Ngo, Hyungyu Choi, Min Sup Choi, Wonki Lee, Tuan Dung Nguyen, Trang Thu Tran, Kwangro Lee, Jun Yeon Hwang, Jeongyong Kim, Won Jong Yoo
Abstract
Doping is one of the most difficult technological challenges for realizing reliable two-dimensional (2D) material-based semiconductor devices, arising from their ultrathinness. Here, we systematically investigate the impact of different types of nonstoichiometric solid MO x (M are W or Mo) dopants obtained by oxidizing transition metal dichalcogenides (TMDs: WSe 2 or MoS 2 ) formed on graphene FETs, which results in p -type doping along with disorders. From the results obtained in this study, we were able to suggest an analytical technique to optimize the optimal UV-ozone (UVO) treatment to achieve high p -type doping concentration in graphene FETs (∼2.5 × 10 13 cm –2 in this study) without generating defects, mainly by analyzing the time dependency of D and D ′ peaks measured by Raman spectroscopy. Furthermore, an analysis of the structure of graphene sheets using TEM indicates that WO x plays a better protective role in graphene, compared to MoO x, suggesting that WO x is more effective for preventing the degradation of graphene during UVO treatment. To enhance the practical application aspect of our work, we have fabricated a graphene photodetector by selectively doping the graphene through oxidized TMDs, creating a p – n junction, which resulted in improved photoresponsivity compared to the intrinsic graphene device. Our results offer a practical guideline for the utilization of surface charge transfer doping of graphene toward CMOS applications.