Controlled p-Type Doping of MoS2 Monolayer by Copper Chloride

Abstract

Electronic devices based on two-dimensional (2D) MoS2 show great promise as future building blocks in electronic circuits due to their outstanding electrical, optical, and mechanical properties. Despite the high importance of doping of these 2D materials for designing field-effect transistors (FETs) and logic circuits, a simple and controllable doping methodology still needs to be developed in order to tailor their device properties. Here, we found a simple and effective chemical doping strategy for MoS2 monolayers using CuCl2 solution. The CuCl2 solution was simply spin-coated on MoS2 with different concentrations under ambient conditions for effectively p-doping the MoS2 monolayers. This was systematically analyzed using various spectroscopic measurements using Raman, photoluminescence, and X-ray photoelectron and electrical measurements by observing the change in transfer and output characteristics of MoS2 FETs before and after CuCl2 doping, showing effective p-type doping behaviors as observed through the shift of threshold voltages (Vth) and reducing the ON and OFF current level. Our results open the possibility of providing effective and simple doping strategies for 2D materials and other nanomaterials without causing any detrimental damage.

Energy level modulation of MoS2monolayers by halide doping for an enhanced hydrogen evolution reaction

“…From Fig. S3c and d 19,26,30,32,40 For further verication of the relationship between carrier transport dynamics and energy level engineering in MoS 2 monolayers, electrical measurement was conducted for pristine and halide doped MoS 2 eld-effect transistors (FETs). Hafnium oxide (HfO 2 ) was used as the gate oxide layer, and Ti/Au (5 nm/ 45 nm) was used as the metal electrode material as shown in Fig.…”

“…This analysis indicates that halide doping methods effectively donate and withdraw electrons from the MoS 2 monolayer, respectively, which consequently change the Fermi level of MoS 2 monolayers. 19,26,30,32,40…”

“…These electrical properties of halide doped MoS 2 devices showed significantly different behavior. 18,32,37,41,42 In parallel-plate capacitor model calculation, the estimated charge carrier densities are 3.01 × 10 12 cm −2 and 2.19 × 10 12 cm −2 for the Cl-MoS 2 device and I-MoS 2 device, respectively. We further evaluated the modulation of the mobility of pristine and halide doped MoS 2 FETs, which are 10.3, 30.1, and 6.3 cm 2 V −1 s −1 for the pristine-MoS 2 , Cl-MoS 2 and I-MoS 2 FETs, respectively.…”

“…To identify the relationship between the energy levels and corresponding catalytic behaviors, opposite types of dopants (Cl and I) were employed to increase or decrease the Fermi level of MoS 2 monolayers, which was evaluated through various spectroscopic and electrical measurements. 19,23,[30][31][32][33] The energy level variation in MoS 2 monolayers sensitively changes the conductance and potential barrier at both electrode-catalyst and catalyst-electrolyte interfaces, which directly affected the catalytic performance of MoS 2 monolayers. To further analyze the role of each potential barrier at the electrode-catalyst and the catalyst-electrolyte interface, we fabricated two types of devices where the surface of MoS 2 monolayers was locally and fully doped.…”

Direct CVD Synthesis of MoS2 Monolayers on Glass by Carbothermal Reduction

“…Atomically thin two-dimensional (2D) transition-metal dichalcogenides (TMDCs, MX 2 , where M and X represent transition-metal ions and chalcogen ions, respectively) have attracted tremendous research interest in both theoretical and technological studies due to their excellent electrical, mechanical, and chemical properties. − Among them, molybdenum disulfide (MoS 2 ) has been extensively studied in electronics, optoelectronics, and flexible and wearable devices. − Especially, its dangling-bond-free surface and atomic thickness offer transparency with moderate band gap energy, good carrier mobility, highly efficient light absorption, and integration on various substrates and materials, suitable for the realization of future nanoscale devices. , …”