Study of Electrical Behavior of Metal‐Semiconductor Contacts on Exfoliated MoS₂ Flakes

Abstract

While 2D materials have been investigated for their potential applications in nanoelectronic and optoelectronic devices, their functionality is still not fully explored due to lack of proper understanding of metal contacts on these materials. The present work pertains to the study of electrical behavior of different metals such as chromium, silver, nickel, and platinum deposited on to exfoliated MoS 2 flakes. Comparative study of different metal contacts to MoS 2 shows that Ag/Au exhibits good ohmic behavior with high current injection efficiency and better linearity and symmetry of I-V curves than Cr/ Au and Ni/Au contacts. Specific contact resistivity is measured to be 4.54 Â 10 À4 Ω cm 2 using transmission line measurement (TLM) for Ag/MoS 2 contacts. Further, taking Ag/Au as ohmic contact, Pt/MoS 2 Schottky barrier diode is fabricated with a high rectification ratio of about 900. Barrier height and ideality factor of 0.56 eV and 2.1, respectively are obtained. This study opens up the possibility of having high quality metal contacts on MoS 2 with potential applications in nanoscale devices.

Enhanced Gas Sensing Performance of Surface‐Activated MoS2 Nanosheets Made by Hydrothermal Method with Excess Sulfur Precursor

“…The Raman spectra showed two peaks corresponding to the E 1 2g and A 1g modes of MoS 2, located at 379.1 and 403.5 cm −1 , respectively, without any secondary phase. These peak positions did not change with different S/Mo precursor ratios, revealing that the thickness of all samples was similar, because the distance between peaks of the E 1 2g and A 1g peaks of MoS 2 is related to the nanosheet thickness . Although the nanosheet size and thickness of the samples were similar, as mentioned earlier, the samples showed different S BET values.…”

“…These peak positions did not change with different S/Mo precursor ratios, revealing that the thickness of all samples was similar, because the distance between peaks of the E 1 2g and A 1g peaks of MoS 2 is related to the nanosheet thickness. [24,25] Although the nanosheet size and thickness of the samples were similar, as mentioned earlier, the samples showed different S BET values. The S BET value showed a sharp increase from 133.5 to 159.6 m 2 g À1 when the S/Mo precursor ratio was increased from 2 to 3, and then gradually increased to 184.6 m 2 g À1 at an S/Mo precursor ratio of 12.…”

High-Temperature Performance of a GaSe Nanosheet-Based Broadband Photodetector

“…They are extensively used in the fields of space communication, biological recognition, chemical detection, and tracking down flame particles . Several oxides like copper oxide (CuO) and β-gallium oxide (Ga 2 O 3 ); a few nitrides like gallium nitride (GaN) and aluminium gallium nitride (AlGaN); and recently, some two-dimensional (2D) nanostructured materials are being utilized immensely to design and develop photodetectors . The two main reasons behind the gigantic exploitation of nanostructures in the fabrication of photodetectors are: first, their nano-size and high surface-to-volume ratio facilitate achieving a higher photosensitivity than their bulk counterpart, and the lifetime of a photocarrier is increased noticeably by the surface states which boost charge separation.…”

“…2 Several oxides like copper oxide (CuO) 3 and β-gallium oxide (Ga 2 O 3 ); 4 a few nitrides like gallium nitride (GaN) 5 and aluminium gallium nitride (AlGaN); 6 and recently, some two-dimensional (2D) nanostructured materials are being utilized immensely to design and develop photodetectors. 7 The two main reasons behind the gigantic exploitation of nanostructures in the fabrication of photodetectors are: first, their nano-size and high surface-tovolume ratio facilitate achieving a higher photosensitivity than their bulk counterpart, and the lifetime of a photocarrier is increased noticeably by the surface states which boost charge separation. Second, the strong dependence of bandgap on the size of nanostructured materials is very helpful in designing multispectral photodetectors, within a single material system, which can work in visible, near-infrared, and ultraviolet regions.…”

Ultrafast flash memory with large self-rectifying ratio based on atomically thin MoS2-channel transistor

“…Figures 2(b) and S3 show the typical output curves (drain current, I D , versus drain-to-source voltage, V DS ) of the MoS 2 -channel FET. The linear increase in I D as a function of V DS proves the existence of good Ohmic-like contact between the MoS 2 channel and Cr/Au metal electrode [27][28][29]. In addition, according to the transfer curves (I D versus V BG ) in figure 2(c), the MoS 2 conduction channel exhibits a strong ntype behaviour with a threshold voltage (V TH ) of ∼−25 V. Thus, a high-performance MoS 2 -channel FET with approximate Ohmic contact and high injection current (∼15 µA at V DS = ±1 V and V BG = −20 V) was demonstrated using this method.…”