Metal-Contact Improvement in a Multilayer WSe₂ Transistor through Strong Hot Carrier Injection

Hot carrier injection (HCI), occurring when the horizontal electric field is strongly applied, usually affects the degradation of nanoelectronic devices. In addition, metal contacts play a significant role in nanoelectronic devices. In this study, Schottky contacts in multilayer tungsten diselenide (WSe₂) field-effect transistors (FETs) by hot carrier injection (HCI), occurring when a high drain voltage is applied, is investigated. A small number of hot carriers with high energy reduces the Schottky barrier height and improves the performance of FETs effectively rather than damaging the channel. Thermal annealing at the end of the fabrication process increases device performance by causing interfacial reactions of the source/drain electrodes. HCI causes a significant enhancement in the local asymmetry, especially in the subthreshold region. The subthreshold swing (SS) of the thermally annealed FETs is significantly improved from 9.66 to 0.562 V dec^-1 through the energy of HCI generated by a strong horizontal electric field. In addition, the contact resistances (R_SD), also called series resistances, extracted by a four-probe measurement and a Y-function method were also improved by decreasing to a 10th through the energy of HCI. To understand the asymmetrical characteristics of the channel after the stress, we performed electrical analysis, electrostatic force microscopy (EFM), and Raman spectroscopy.