WS₂/GeSe/WS₂ Bipolar Transistor-Based Chemical Sensor with Fast Response and Recovery Times

Abstract

Vertical heterostructures of transition-metal dichalcogenide semiconductors have attracted considerable attention and offer new opportunities in electronics and optoelectronics for the development of innovative and multifunctional devices. Here, we designed a novel and compact vertically stacked two-dimensional (2D) n-WS2/p-GeSe/n-WS2 van der Waals (vdW) heterojunction bipolar transistor (2D-HBT)-based chemical sensor. The performance of the 2D-HBT vdW heterostructure with different base thicknesses is investigated by two configurations, namely, common-emitter and common-base configurations. The 2D-HBT vdW heterostructure exhibited intriguing electrical characteristics of current amplification with large gains of α ≈ 1.11 and β ≈ 20.7. In addition, 2D-HBT-based devices have been investigated as chemical sensors for the detection of NH3 and O2 gases at room temperature. The effects of different environments, such as air, vacuum, O2, and NH3, were also analyzed in dark conditions, and with a light of 633 nm wavelength, ultrahigh sensitivity and fast response and recovery times (6.55 and 16.2 ms, respectively) were observed. These unprecedented outcomes have huge potential in modern technology in the development of low-power amplifiers and gas sensors.

A Multifunctional Flexible Ferroelectric Transistor Sensor for Electronic Skin

“…[ 11 ] Such FET devices can be easily attached to any bendable or specially shaped surfaces to extend their functions. [ 11a ] Especially, in recent years the FET has been developed as sensing devices [ 12 ] to perceive and recognize, e.g., NH 3 and O 2 gases, [ 13 ] DNA, [ 14 ] light, [ 15 ] force, [ 16 ] and charged object. [ 17 ] Furthermore, as one part of E‐skin, FET‐based sensors possess several advantages including excellent electric and mechanical properties, [ 18 ] reduced crosslink between pixels for precise signal distribution mapping, [ 19 ] and less cost compared with complementary metal oxide semiconductor technology.…”

High performance and gate-controlled GeSe/HfS2 negative differential resistance device

“…The energy band diagram of the GeSe with different metals before and aer contact between the metals and the GeSe material is shown in Fig.S4. † The values of the work functions, electron affinities and bandgaps of GeSe and n-HfS 2 were taken from previously reported studies 41,[48][49][50][51][52][53][54][55][56].…”

Formation of van der Waals Stacked p–n Homojunction Optoelectronic Device of Multilayered ReSe2 by Cr Doping

“…In the post-silicon era, newgeneration van der Waals materials such as two-dimensional (2D) semiconductors have received extensive attention and research due to their practical advantages of smooth surface, [1,2] high mobility, [3] ultrathin, [4] flexibility, [5,6] in-plane structural and optical anisotropy, [7][8][9][10] thickness-dependent carrier conduction, [11] thickness tunable bandgap, [12,13] and abundance of direct band-edge excitons. [14,15] Among them, transition metal dichalcogenides (TMDs), including four popular members, MoS 2 , MoSe 2 , WS 2 , and WSe 2 , have been vigorously studied and have potential capabilities in practical semiconductor device applications such as field-effect transistors, [16] bipolar junction transistors, [17,18] phototransistors, [19] and light-emitting diodes (LEDs), [20] etc., due to their high environmental stability and the flexibility on thickness tuning bandgaps. The growth of p-and n-type materials in TMDs layers may be a key issue for the development of various p-n junction devices in 2D semiconductor technology.…”

“…However, to date, the synthesis of p-type layered TMDs is still challenging, and even some proposals have been made related to Nbdoped p-MoSe 2 , [21] Nb-doped p-MoS 2 , [22] oxygen plasma doped p-MoS 2 , [23] and nitrogen-induced p-WS 2 , [24] etc., the information on the ideal dopants for forming p-type TMDs with controllable carrier concentration and good stability is still insufficient and needs to be further explored. Nowadays, many TMD bipolar p-n junction devices and LEDs typically operate in gate-controlled p-and n-type with a lateral junction, [20,25,26] and a large number of vertically stacked 2D layered devices are still fabricated as heterostructures and heterojunctions [17,18] because of the lack of van der Waals stacked p-n homojunction.Compared to conventional MoS 2 , MoSe 2 , WS 2 , and WSe 2 dichalcogenides, rhenium diselenide (ReSe 2 ) is also an important member of the TMD-family 2D semiconductors, which crystallizes in a specific distorted CdI 2 -type layered structure of triclinic symmetry (space group P1). [27,28] Dissimilar to that the MoS 2 group has a uniform and isotropic layer plane in generally two-layer hexagonal or three-layer rhombohedral form, the structural distortion in the CdI 2 -type (i.e., 1T′) ReSe 2 layer may cause by a specific d 3 nonbonding Re-Re interaction and which The formation of p-or n-type material via impurity doping should be crucial and essentially prior to the establishment of junction devices in semiconductor processing.…”