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

Abstract

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.

Deep Understanding of Electron Beam Effects on 2D Layered Semiconducting Devices Under Bias Applications

“…[9][10][11] Among them, molybdenum disulfide (MoS 2 ) and tungsten diselenide (WSe 2 ) are most popular 2D semiconducting materials and have been widely studied for the next-generation electronic applications. [12,13] MoS 2 is typically known as an n-type material [14,15] and WSe 2 shows an ambipolar characteristic because of its In this study, the radiation effects of electron beam (e-beam) on field-effect transistors (FETs) using transition-metal dichalcogenides (TMD) as a channel are carefully investigated. Electron-hole pairs (EHPs) in SiO 2 generated by e-beam irradiation induce additional traps, which change the surface potential of the TMD channel, resulting in strong negative shifts of transfer characteristics.…”

“…[ 9–11 ] Among them, molybdenum disulfide (MoS 2 ) and tungsten diselenide (WSe 2 ) are most popular 2D semiconducting materials and have been widely studied for the next‐generation electronic applications. [ 12,13 ] MoS 2 is typically known as an n‐type material [ 14,15 ] and WSe 2 shows an ambipolar characteristic because of its higher positions of the conduction band minimum and valance band maximum. [ 16,17 ] Advanced technologies using electron beams (e‐beam) such as scanning electron microscope (SEM), [ 5,18 ] transmission electron microscope (TEM), [ 18,19 ] and e‐beam lithography (EBL) [ 20 ] offer an effective platform for fabrication and structural analysis of 2D layered materials.…”

Modeling and Understanding the Compact Performance of h‐BN Dual‐Gated ReS2 Transistor

“…[1] Transition-metal dichalcogenide (TMD) materials are promising candidates to replace the Si channel because of their high carrier mobility, excellent applicability, mechanical, optical, and electrical properties. [2][3][4][5][6][7][8][9][10] Among these numerous TMD materials, rhenium disulfide (ReS 2 ) has a distorted 1T structure [11] with higher interlayer resistance (R int ) compared to other TMD materials, [12,13] and anisotropic electrical and optical properties. [13,14] Recently, in comparison with the well-known molybdenum disulfide (MoS 2 ), which has the 2H phase, ReS 2 has attracted significant attention because of its direct bandgap from single layer to bulk since each layer is decoupled from the other.…”

Cyclic Thermal Effects on Devices of Two‐Dimensional Layered Semiconducting Materials

“…[ 12–14 ] Therefore, circuits based on TMD materials require further research in the fields of metal contact, patterning, encapsulation, temperature dependence, and reliability. [ 13–19 ] Since TMD devices have a large surface/volume ratio and are highly affected by charge transferring of adsorbates such as H 2 O and O 2 , encapsulation is essential. [ 20 ] Encapsulation and temperature cause variations in the interfaces of the TMD devices, and consequently have a great influence on the performance and reliability of the device.…”

“…Indeed, the effect of Joule heating on the operating temperature, which occurs while the device is operating, cannot be ignored. [ 15,30,31 ] When the device repeatedly turns on/off under the low temperature, the operating temperature changes rapidly.…”