Enhanced contact properties of MoTe₂-FET via laser-induced heavy doping

Abstract

Doping technique is vital for applying two-dimensional (2D) materials such as transition metal dichalcogenide (TMDC)-based field effect transistors (FETs), which can control the channel polarity and improve the performance. However, as conventional doping techniques for silicon-based FET are not suitable for 2D materials, the realization of heavy doping of TMDC materials is challenging, especially for n-type heavy doping. This study reports a simple, regioselective, controllable, and chemically stable heavy doping method for 2H-MoTe2 crystal via high-density laser irradiation. The polarity of the doping can be controlled by changing the irradiation environment. For the MoTe2-nFET, good performance with enhanced contact properties was obtained using the contact doping method via laser irradiation in a vacuum environment.

Realization of MoTe2 CMOS inverter by contact doping and channel encapsulation

“…In the condition of laser irradiation in an atmospheric environment, oxygen molecules quickly adsorb into the Te vacancies induced by laser in the region around the irradiated area, forming a strong acceptor energy level, making this region heavily p-type doped. 35) Figure 1(f) shows the optical image of the sample after laser irradiation. Here, the doping levels under these two conditions were confirmed by measuring their transfer characteristics (I d -V g ), as shown in Fig.…”

“…Hence, the Schottky barrier can be estimated using the thermionic equations as outlined in our previous study. 35) By fitting the Arrhenius plot of current, the Schottky barrier at each gate voltage can be extracted, as illustrated in Figs. 3(b) and 3(e).…”

“…Furthermore, the contact properties have been enhanced through the laser-induced contact doping method, as detailed in our previous research. 35) In this study, we successfully realized contact-optimized n-and p-channel MoTe 2 -FETs through laser-induced contact doping processes on an h-BN substrate, conducted in vacuum and ambient environments, respectively. Additionally, to enhance carrier mobility and safeguard the channel from external perturbations, an h-BN encapsulation has been applied to both FETs' channels.…”